Non-optimal solutions when solving an aTSP with Gurobi

Hi, I'm trying to solve an Asymmetric Travelling Salesman Problem using the following formulation:

GRBEnv env = new GRBEnv(true);
        env.Start();

        GRBModel model = new GRBModel(env);

        //Gurobi Parameters
        model.Parameters.TimeLimit = 3600;

        //Variables
        GRBVar[,] x = new GRBVar[numberOfNodes, numberOfNodes];
        GRBVar[] u = new GRBVar[numberOfNodes];
        for (int i=0; i<numberOfNodes; i++)
        {
            if (i > 0)
            {
                u[i] = model.AddVar(1, numberOfNodes - 1, 0, GRB.INTEGER, "u");
            }
            for(int j=0; j<numberOfNodes; j++)
            {
                if (i != j)
                {
                    x[i, j] = model.AddVar(0, 1, distancematrix[i, j], GRB.BINARY, "x");
                }
            }
        }

        //Objective
        model.ModelSense = GRB.MINIMIZE;

        //Constraints
        for(int i=0; i<numberOfNodes; i++)
        {
            GRBLinExpr edgesIn = new GRBLinExpr();
            GRBLinExpr edgesOut = new GRBLinExpr();
            for(int j=0; j<numberOfNodes; j++)
            {
                if (i != j)
                {
                    edgesIn.AddTerm(1, x[j, i]);
                    edgesOut.AddTerm(1, x[i, j]);

                    if(i>0 && j > 0)
                    {
                        model.AddConstr(u[i] - u[j] + numberOfNodes * x[i, j], GRB.LESS_EQUAL, numberOfNodes - 1, "subtourElimination1");
                    }
                }
            }
            model.AddConstr(edgesIn, GRB.EQUAL, 1, "edgesIn");
            model.AddConstr(edgesOut, GRB.EQUAL, 1, "edgesOut");
        }


        model.Optimize();
}

Although it works for most cases, there are instances for which Gurobi suggests a non-optimal solution (but declares it as optimal). For example, when handing Gurobi the following distance parameters as "distancematrix" (sorry for the messy visualization):

{ {0,43618,43620,43628,43615,43616,43617,43624,43627,43629,43632,43611,43616,43620,43622,43629,43620,43621,43612,43618,43606,43609,43610,43613,43616,43617,43618,43619,43620,43621,43605,43617,43619,43608,43612,43613,43616,43617,43619,43622,43613,43614,43615,43617,43618,43620,43629,43614,43615,43616,43618,43624,43633},
{43615,0,43609,43617,0,43600,43600,43609,43612,43614,43617,43606,43600,43615,43617,43600,43621,43622,43619,43625,43600,43622,43623,43626,43629,43630,43631,43632,43600,43632,43618,43630,43600,43600,43625,43600,43629,43630,43632,43635,43626,43627,43628,43630,43631,43600,43600,43627,43628,43600,43631,43637,43600},
{43624,43616,0,43622,43609,43608,43607,0,43603,43605,43608,43600,43620,43624,43622,43615,43624,43600,43600,43600,43628,43600,43600,43631,43600,43600,43626,43600,43624,43623,43600,43633,43631,43630,43634,43635,43638,43600,43600,43600,43635,43636,43637,43600,43600,43642,43633,43600,43600,43638,43600,43644,43635},
{43627,43619,43621,0,43612,43611,43610,43603,0,43600,43600,43618,43623,43600,43600,43612,43600,43620,43629,43623,43631,43632,43631,43600,43625,43624,43600,43622,43621,43600,43630,43600,43628,43633,43600,43638,43600,43636,43634,43631,43600,43600,43600,43642,43641,43639,43630,43639,43640,43641,43643,43600,43632},
{43616,43600,43610,43618,0,0,43600,43608,43611,43613,43616,43607,43600,43616,43618,43600,43622,43623,43620,43626,43600,43623,43624,43627,43630,43631,43632,43633,43600,43631,43619,43631,43600,43600,43626,43600,43630,43631,43633,43636,43627,43628,43629,43631,43632,43600,43600,43628,43629,43600,43632,43638,43600},
{43617,43600,43611,43619,43600,0,0,43607,43610,43612,43615,43608,43600,43617,43619,43600,43623,43624,43621,43627,43600,43624,43625,43628,43631,43632,43633,43632,43600,43630,43620,43632,43600,43600,43627,43600,43631,43632,43634,43637,43628,43629,43630,43632,43633,43600,43600,43629,43630,43600,43633,43639,43600},
{43616,43600,43616,43624,43600,43600,0,43620,43623,43623,43620,43605,0,43604,43606,43600,43622,43623,43620,43626,43600,43623,43624,43627,43630,43629,43628,43627,43600,43625,43619,43631,43600,43600,43626,43600,43630,43631,43633,43636,43627,43628,43629,43631,43632,43600,43600,43628,43629,43600,43632,43638,43600},
{43611,43609,43600,43619,43606,43607,43608,0,43618,43620,43623,0,43605,43609,43611,43618,43617,43600,43600,43600,43615,43600,43600,43622,43600,43600,43627,43600,43629,43630,43600,43626,43628,43617,43621,43622,43625,43600,43600,43600,43622,43623,43624,43600,43600,43629,43638,43600,43600,43625,43600,43633,43642},
{43629,43621,43623,43600,43614,43613,43612,43605,0,0,43600,43620,43623,43600,43600,43610,43600,43618,43627,43621,43633,43630,43629,43600,43623,43622,43600,43620,43619,43600,43632,43600,43626,43635,43600,43638,43600,43634,43632,43629,43600,43600,43600,43640,43639,43637,43628,43641,43642,43643,43645,43600,43630},
{43632,43624,43622,43600,43617,43616,43615,43608,43600,0,0,43623,43620,43600,43600,43607,43600,43615,43624,43618,43630,43627,43626,43600,43620,43619,43600,43617,43616,43600,43635,43600,43623,43638,43600,43635,43600,43631,43629,43626,43600,43600,43600,43637,43636,43634,43625,43644,43645,43644,43642,43600,43627},
{43620,43618,43620,43600,43615,43616,43617,43624,43600,43600,0,43609,43604,0,43600,43609,43600,43621,43624,43624,43624,43627,43628,43600,43626,43625,43600,43623,43622,43600,43623,43600,43629,43626,43600,43631,43600,43635,43635,43632,43600,43600,43600,43635,43636,43638,43631,43632,43633,43634,43636,43600,43633},
{43621,43625,43600,43625,43622,43623,43624,43600,43620,43618,43615,0,43623,43621,43619,43612,43601,0,43600,43600,43625,43600,43600,43622,43600,43600,43617,43600,43615,43614,43600,43624,43622,43627,43631,43632,43631,43600,43600,43600,43632,43633,43634,43600,43600,43633,43624,43600,43600,43635,43600,43635,43626},
{43629,43600,43625,43617,43600,43600,43600,43615,43612,43610,43607,43618,0,43609,43607,0,43613,43612,43621,43615,43600,43624,43623,43620,43617,43616,43615,43614,43600,43612,43632,43622,43600,43600,43633,43600,43629,43628,43626,43623,43638,43637,43636,43634,43633,43600,43600,43641,43642,43600,43639,43633,43600},
{43622,43620,43622,43600,43617,43618,43619,43622,43600,43600,43600,43611,43606,0,0,43607,43600,43619,43626,43622,43626,43629,43630,43600,43624,43623,43600,43621,43620,43600,43625,43600,43627,43628,43600,43633,43600,43635,43633,43630,43600,43600,43600,43637,43638,43638,43629,43634,43635,43636,43638,43600,43631},
{43620,43624,43626,43600,43621,43622,43623,43624,43600,43600,43600,43617,43622,43600,0,43613,0,43601,43624,43618,43624,43627,43626,43600,43620,43619,43600,43617,43616,43600,43623,43600,43623,43626,43600,43631,43600,43631,43629,43626,43600,43600,43600,43635,43636,43634,43625,43632,43633,43634,43636,43600,43627},
{43606,43600,43624,43632,43600,43600,43600,43628,43631,43633,43630,43615,43600,43624,43626,0,43624,43625,43616,43622,0,43603,43604,43607,43610,43611,43612,43613,43600,43615,43609,43621,43600,43600,43616,43600,43620,43621,43623,43626,43617,43618,43619,43621,43622,43600,43600,43618,43619,43600,43622,43628,43600},
{43613,43629,43631,43600,43626,43627,43628,43631,43600,43600,43600,43622,43627,43600,43600,43620,0,43622,43623,43619,43607,43604,43603,0,43603,43604,43600,43606,43607,43600,43616,43600,43618,43619,43600,43624,43600,43626,43624,43621,43600,43600,43600,43628,43629,43629,43620,43625,43626,43627,43629,43600,43622},
{43612,43622,43600,43632,43619,43620,43621,43600,43629,43627,43624,43600,43620,43624,43626,43621,43624,0,0,43600,43616,43600,43600,43623,43600,43600,43620,43600,43618,43617,43600,43627,43625,43618,43622,43623,43626,43600,43600,43600,43623,43624,43625,43600,43600,43630,43627,43600,43600,43626,43600,43634,43629},
{43618,43628,43600,43628,43625,43626,43627,43600,43623,43621,43618,43600,43626,43624,43622,43615,43618,43600,0,0,43622,43600,43600,43619,43600,43600,43614,43600,43612,43611,43600,43621,43619,43624,43628,43629,43628,43600,43600,43600,43629,43630,43631,43600,43600,43630,43621,43600,43600,43632,43600,43632,43623},
{43609,43625,43600,43635,43622,43623,43624,43600,43632,43630,43627,43600,43623,43627,43629,43624,43627,43600,43600,0,43603,0,43600,43604,43600,43600,43609,43600,43611,43612,43600,43624,43622,43615,43619,43620,43623,43600,43600,43600,43620,43621,43622,43600,43600,43627,43624,43600,43600,43623,43600,43631,43626},
{43620,43600,43634,43626,43600,43600,43600,43624,43621,43619,43616,43629,43600,43622,43620,43600,43616,43615,43618,43612,0,43611,43610,43607,43604,43603,43602,43601,0,43601,43623,43613,43600,43600,43624,43600,43620,43619,43617,43614,43629,43628,43627,43625,43624,43600,43600,43632,43633,43600,43630,43624,43600},
{43610,43626,43600,43636,43623,43624,43625,43600,43631,43629,43626,43600,43624,43628,43630,43623,43626,43600,43600,43600,43604,0,0,43603,43600,43600,43608,43600,43610,43611,43600,43623,43621,43616,43620,43621,43624,43600,43600,43600,43621,43622,43623,43600,43600,43628,43623,43600,43600,43624,43600,43632,43625},
{43616,43632,43600,43630,43629,43630,43631,43600,43625,43623,43620,43600,43630,43626,43624,43617,43620,43600,43600,43600,43610,43600,0,43603,0,43600,43602,43600,43604,43605,43600,43617,43615,43622,43626,43627,43624,43600,43600,43600,43627,43628,43629,43600,43600,43626,43617,43600,43600,43630,43600,43628,43619},
{43618,43634,43636,43600,43631,43632,43633,43626,43600,43600,43600,43627,43628,43600,43600,43615,43600,43617,43620,43614,43612,43609,43608,0,43602,43601,0,43601,43602,43600,43621,43600,43613,43624,43600,43625,43600,43621,43619,43616,43600,43600,43600,43627,43626,43624,43615,43630,43631,43632,43632,43600,43617},
{43617,43633,43600,43629,43630,43631,43632,43600,43624,43622,43619,43600,43629,43625,43623,43616,43619,43600,43600,43600,43611,43600,43600,43604,0,0,43601,43600,43603,43604,43600,43616,43614,43623,43627,43626,43623,43600,43600,43600,43628,43629,43630,43600,43600,43625,43616,43600,43600,43631,43600,43627,43618},
{43619,43635,43600,43627,43632,43633,43632,43600,43622,43620,43617,43600,43627,43623,43621,43614,43617,43600,43600,43600,43613,43600,43600,43606,43600,0,43601,0,43601,43602,43600,43614,43612,43625,43625,43624,43621,43600,43600,43600,43630,43629,43628,43600,43600,43623,43614,43600,43600,43633,43600,43625,43616},
{43621,43635,43633,43600,43632,43631,43630,43623,43600,43600,43600,43630,43625,43600,43600,43612,43600,43614,43617,43611,43615,43612,43611,43600,43605,43604,0,43602,43601,0,43624,43600,43610,43627,43600,43622,43600,43618,43616,43613,43600,43600,43600,43624,43623,43621,43612,43633,43632,43631,43629,43600,43614},
{43605,43621,43600,43631,43618,43619,43620,43600,43630,43632,43635,43600,43619,43623,43625,43632,43623,43600,43600,43600,43609,43600,43600,43616,43600,43600,43621,0,43623,43624,0,43612,43614,43605,43609,43610,43613,43600,43600,43600,43610,43611,43612,43600,43600,43617,43626,43600,43600,43613,43600,43621,43630},
{43619,43600,43637,43633,43600,43600,43600,43631,43628,43626,43623,43628,43600,43629,43627,43600,43623,43622,43625,43619,43600,43622,43621,43618,43615,43614,43613,43612,0,43610,43614,43602,0,43600,43623,43600,43621,43620,43618,43615,43624,43625,43626,43626,43625,43600,43600,43625,43626,43600,43629,43625,43600},
{43617,43633,43635,43600,43630,43631,43632,43633,43600,43600,43600,43626,43631,43600,43600,43622,43600,43624,43627,43621,43621,43624,43623,43600,43617,43616,43600,43614,43613,0,43612,0,43602,43617,43600,43622,43600,43622,43620,43617,43600,43600,43600,43626,43627,43625,43616,43623,43624,43625,43627,43600,43618},
{43617,43633,43600,43641,43630,43631,43632,43600,43636,43634,43631,43600,43631,43635,43635,43628,43631,43600,43600,43600,43621,43600,43600,43626,43600,43600,43621,43600,43619,43618,0,43622,43620,43609,43605,43604,43601,0,43600,43600,43616,43617,43618,43600,43600,43623,43616,43600,43600,43619,43600,43627,43618},
{43612,43628,43630,43600,43625,43626,43627,43634,43600,43600,43600,43621,43626,43600,43600,43633,43600,43631,43622,43628,43616,43619,43620,43600,43626,43627,43600,43625,43624,43600,43609,0,43623,43604,0,43601,43600,43605,43607,43610,43600,43600,43600,43615,43616,43618,43621,43612,43613,43614,43616,43600,43623},
{43608,43600,43626,43634,43600,43600,43600,43630,43633,43635,43638,43617,43600,43626,43628,43600,43626,43627,43618,43624,43600,43615,43616,43619,43622,43623,43624,43625,43600,43627,43605,43617,0,0,43604,43600,43608,43609,43611,43614,43607,43608,43609,43611,43612,43600,43600,43608,43609,43600,43612,43618,43600},
{43613,43600,43631,43639,43600,43600,43600,43635,43638,43638,43635,43622,43600,43631,43633,43600,43631,43632,43623,43629,43600,43620,43621,43624,43627,43626,43625,43624,43600,43622,43610,43622,43600,0,43601,0,43603,43604,43606,43609,43612,43613,43614,43616,43617,43600,43600,43613,43614,43600,43617,43623,43600},
{43616,43632,43634,43600,43629,43630,43631,43638,43600,43600,43600,43625,43630,43600,43600,43629,43600,43631,43626,43628,43620,43623,43624,43600,43624,43623,43600,43621,43620,43600,43613,43600,43621,43608,0,43603,0,43601,43603,43606,43600,43600,43600,43619,43620,43622,43617,43616,43617,43618,43620,43600,43619},
{43620,43600,43638,43644,43600,43600,43600,43642,43639,43637,43634,43629,43600,43638,43638,43600,43634,43633,43630,43630,43600,43627,43628,43629,43626,43625,43624,43623,43600,43621,43617,43625,43600,43600,43618,0,43622,43623,43623,43620,43607,43606,43605,43603,43602,0,43600,43614,43615,43600,43618,43624,43600},
{43613,43629,43631,43600,43626,43627,43628,43635,43600,43600,43600,43622,43627,43600,43600,43638,43600,43632,43623,43629,43617,43620,43621,43600,43627,43628,43600,43630,43629,43600,43610,43600,43624,43607,43600,43612,0,43616,43618,43621,0,43600,43600,43604,43605,43607,43616,43607,43608,43609,43611,43600,43622},
{43619,43635,43600,43639,43632,43633,43634,43600,43634,43632,43629,43600,43633,43635,43633,43626,43629,43600,43600,43600,43623,43600,43600,43624,43600,43600,43619,43600,43617,43616,43600,43620,43618,43611,43607,43606,43603,0,0,43600,43618,43619,43620,43600,43600,43623,43614,43600,43600,43621,43600,43625,43616},
{43622,43638,43600,43636,43635,43636,43637,43600,43631,43629,43626,43600,43636,43632,43630,43623,43626,43600,43600,43600,43626,43600,43600,43621,43600,43600,43616,43600,43614,43613,43600,43617,43615,43614,43610,43609,43606,43600,0,0,43621,43622,43623,43600,43600,43620,43611,43600,43600,43624,43600,43622,43613},
{43617,43633,43600,43643,43630,43631,43632,43600,43642,43640,43637,43600,43631,43635,43637,43634,43635,43600,43600,43600,43621,43600,43600,43628,43600,43600,43627,43600,43625,43624,43600,43626,43626,43611,43615,43616,43619,43600,43600,0,43604,43603,43602,0,43600,43603,43612,43600,43600,43613,43600,43621,43618},
{43614,43630,43632,43600,43627,43628,43629,43636,43600,43600,43600,43623,43628,43600,43600,43637,43600,43633,43624,43630,43618,43621,43622,43600,43628,43629,43600,43629,43628,43600,43611,43600,43625,43608,43600,43613,43600,43617,43619,43622,0,0,43600,43603,43604,43606,43615,43608,43609,43610,43612,43600,43621},
{43615,43631,43633,43600,43628,43629,43630,43637,43600,43600,43600,43624,43629,43600,43600,43636,43600,43634,43625,43631,43619,43622,43623,43600,43629,43630,43600,43628,43627,43600,43612,43600,43626,43609,43600,43614,43600,43618,43620,43623,43600,0,0,43602,43603,43605,43614,43609,43610,43611,43613,43600,43620},
{43624,43640,43642,43600,43637,43638,43639,43644,43600,43600,43600,43633,43638,43600,43600,43633,43600,43635,43634,43632,43628,43631,43632,43600,43628,43627,43600,43625,43624,43600,43621,43600,43625,43618,43600,43623,43600,43627,43625,43622,43600,43600,0,43621,43622,43624,43615,43610,43609,43608,43606,0,43609},
{43618,43634,43600,43644,43631,43632,43633,43600,43641,43639,43636,43600,43632,43636,43638,43633,43636,43600,43600,43600,43622,43600,43600,43629,43600,43600,43626,43600,43624,43623,43600,43627,43625,43612,43616,43617,43620,43600,43600,43600,43605,43604,43603,0,0,43602,43611,43600,43600,43614,43600,43622,43617},
{43614,43630,43600,43640,43627,43628,43629,43600,43639,43641,43644,43600,43628,43632,43634,43641,43632,43600,43600,43600,43618,43600,43600,43625,43600,43600,43630,43600,43632,43633,43600,43623,43625,43608,43612,43613,43616,43600,43600,43600,43607,43608,43609,43600,0,43614,43623,0,43600,43602,43600,43610,43619},
{43629,43600,43643,43635,43600,43600,43600,43633,43630,43628,43625,43638,43600,43631,43629,43600,43625,43624,43627,43621,43600,43624,43623,43620,43617,43616,43615,43614,43600,43612,43626,43616,43600,43600,43621,43600,43617,43616,43614,43611,43616,43615,43614,43612,43611,0,0,43623,43624,43600,43621,43615,43600},
{43616,43600,43634,43642,43600,43600,43600,43638,43641,43643,43644,43625,43600,43634,43636,43600,43634,43635,43626,43632,43600,43623,43624,43627,43630,43631,43632,43633,43600,43631,43613,43625,43600,43600,43614,43600,43618,43619,43621,43624,43609,43610,43611,43613,43614,43600,0,43602,43601,0,43602,43608,43600},
{43615,43631,43600,43641,43628,43629,43630,43600,43640,43642,43645,43600,43629,43633,43635,43642,43633,43600,43600,43600,43619,43600,43600,43626,43600,43600,43631,43600,43633,43632,43600,43624,43626,43609,43613,43614,43617,43600,43600,43600,43608,43609,43610,43600,43600,43615,43624,0,0,43601,43600,43609,43618},
{43618,43634,43600,43644,43631,43632,43633,43600,43643,43645,43642,43600,43632,43636,43638,43639,43636,43600,43600,43600,43622,43600,43600,43629,43600,43600,43632,43600,43630,43629,43600,43627,43629,43612,43616,43617,43620,43600,43600,43600,43611,43612,43613,43600,43600,43618,43621,43600,0,43602,0,43606,43615},
{43633,43600,43645,43637,43600,43600,43600,43635,43632,43630,43627,43642,43600,43633,43631,43600,43627,43626,43629,43623,43600,43626,43625,43622,43619,43618,43617,43616,43600,43614,43630,43618,43600,43600,43623,43600,43619,43618,43616,43613,43622,43621,43620,43618,43617,43600,43600,43619,43618,0,43615,43609,0},
{43620,43602,0,43608,43609,43610,43611,43600,43621,43623,43622,43600,43616,43620,43622,43625,43626,43600,43600,43600,43624,43600,43600,43631,43600,43600,43636,43600,43634,43633,43600,43635,43637,43626,43630,43631,43634,43600,43600,43600,43631,43632,43633,43600,43600,43638,43643,43600,43600,43634,0,43642,43645},
{43628,43610,43608,0,43617,43618,43619,43622,43600,43600,43600,43619,43624,43600,43600,43617,43600,43625,43632,43628,43632,43635,43636,43600,43630,43629,43600,43627,43626,43600,43631,43600,43633,43634,43600,43639,43600,43641,43639,43636,43600,43600,43600,43643,43644,43644,43635,43640,43641,43642,43644,0,43637},
{43618,0,43602,43610,43600,43600,43600,43616,43619,43621,43624,43609,43600,43618,43620,43600,43624,43625,43622,43628,43600,43625,43626,43629,43632,43633,43634,43635,43600,43635,43621,43633,43600,43600,43628,43600,43632,43633,43635,43638,43629,43630,43631,43633,43634,43600,43600,43630,43631,43600,43634,43640,0} }

Gurobi comes up with a solution of 174428 with a node sequence of:

[0,30,37,38,39,43,44,47,48,50,2,7,11,17,18,19,21,22,24,25,27,34,36,40,41,42,51,3,8,9,10,13,14,16,23,26,29,31,35,45,46,49,52,1,4,5,6,12,15,20,28,32,33]

However, there is a better tour with length 174426 following this path:

[0,23,26,29,31,34,36,40,41,42,51,3,8,9,10,13,14,16,21,22,24,25,27,30,37,38,39,43,44,47,48,50,2,7,11,17,18,19,20,28,32,33,35,45,46,49,52,1,4,5,6,12,15]

While solving, Gurobi prints the following output:

Gurobi Optimizer version 9.1.2 build v9.1.2rc0 (win64)
Thread count: 4 physical cores, 8 logical processors, using up to 8 threads
Optimize a model with 2758 rows, 2808 columns and 13468 nonzeros
Model fingerprint: 0x1f287d8a
Variable types: 0 continuous, 2808 integer (2756 binary)
Coefficient statistics:
  Matrix range     [1e+00, 5e+01]
  Objective range  [4e+04, 4e+04]
  Bounds range     [1e+00, 5e+01]
  RHS range        [1e+00, 5e+01]
Presolve time: 0.02s
Presolved: 2758 rows, 2808 columns, 13468 nonzeros
Variable types: 0 continuous, 2808 integer (2756 binary)
Found heuristic solution: objective 2268296.0000

Root relaxation: objective 8.721515e+04, 119 iterations, 0.00 seconds

    Nodes    |    Current Node    |     Objective Bounds      |     Work
 Expl Unexpl |  Obj  Depth IntInf | Incumbent    BestBd   Gap | It/Node Time

     0     0 87215.1538    0    9 2268296.00 87215.1538  96.2%     -    0s
H    0     0                    392507.00000 87215.1538  77.8%     -    0s
     0     0 147580.462    0   61 392507.000 147580.462  62.4%     -    0s
H    0     0                    174494.00000 147580.462  15.4%     -    0s
     0     0 147580.462    0   62 174494.000 147580.462  15.4%     -    0s
     0     0 174410.000    0   63 174494.000 174410.000  0.05%     -    0s
     0     0 174410.000    0   59 174494.000 174410.000  0.05%     -    0s
     0     0 174410.000    0   34 174494.000 174410.000  0.05%     -    0s
     0     0 174410.000    0   48 174494.000 174410.000  0.05%     -    0s
H    0     0                    174446.00000 174410.000  0.02%     -    0s
H    0     0                    174438.00000 174410.000  0.02%     -    0s
     0     0 174410.000    0    8 174438.000 174410.000  0.02%     -    0s
     0     0 174410.000    0    9 174438.000 174410.000  0.02%     -    0s
     0     0 174410.000    0   46 174438.000 174410.000  0.02%     -    0s
     0     0 174410.000    0   42 174438.000 174410.000  0.02%     -    0s
     0     0 174410.000    0   71 174438.000 174410.000  0.02%     -    0s
     0     0 174410.000    0   58 174438.000 174410.000  0.02%     -    0s
     0     0 174410.000    0    8 174438.000 174410.000  0.02%     -    0s
     0     0 174410.000    0   34 174438.000 174410.000  0.02%     -    0s
     0     0 174410.000    0   19 174438.000 174410.000  0.02%     -    0s
     0     0 174410.000    0   33 174438.000 174410.000  0.02%     -    1s
     0     0 174410.000    0   19 174438.000 174410.000  0.02%     -    1s
     0     0 174410.000    0   12 174438.000 174410.000  0.02%     -    1s
     0     0 174411.222    0   48 174438.000 174411.222  0.02%     -    1s
     0     0 174412.000    0   79 174438.000 174412.000  0.01%     -    1s
     0     0 174412.000    0   68 174438.000 174412.000  0.01%     -    1s
     0     0 174412.000    0   30 174438.000 174412.000  0.01%     -    1s
     0     0 174412.000    0    9 174438.000 174412.000  0.01%     -    1s
     0     0 174412.000    0   42 174438.000 174412.000  0.01%     -    1s
     0     0 174412.000    0   81 174438.000 174412.000  0.01%     -    1s
     0     0 174412.000    0   97 174438.000 174412.000  0.01%     -    1s
     0     0 174412.000    0   82 174438.000 174412.000  0.01%     -    1s
     0     0 174412.000    0   86 174438.000 174412.000  0.01%     -    1s
H    0     0                    174434.00000 174412.000  0.01%     -    1s
     0     0 174412.000    0   10 174434.000 174412.000  0.01%     -    1s
     0     0 174412.000    0   10 174434.000 174412.000  0.01%     -    1s
     0     0 174412.000    0    9 174434.000 174412.000  0.01%     -    2s
     0     0 174412.000    0   70 174434.000 174412.000  0.01%     -    2s
     0     0 174412.000    0   61 174434.000 174412.000  0.01%     -    2s
     0     0 174412.000    0   40 174434.000 174412.000  0.01%     -    2s
     0     0 174412.000    0   40 174434.000 174412.000  0.01%     -    2s
     0     0 174412.000    0   40 174434.000 174412.000  0.01%     -    2s
     0     0 174412.000    0   40 174434.000 174412.000  0.01%     -    2s
     0     0 174412.000    0   25 174434.000 174412.000  0.01%     -    2s
     0     0 174412.000    0    8 174434.000 174412.000  0.01%     -    2s
     0     0 174412.000    0   35 174434.000 174412.000  0.01%     -    2s
     0     0 174412.000    0   40 174434.000 174412.000  0.01%     -    2s
     0     0 174412.000    0    8 174434.000 174412.000  0.01%     -    2s
     0     2 174412.000    0    8 174434.000 174412.000  0.01%     -    2s
H    4     4                    174428.00000 174412.150  0.01%  59.8    2s

Cutting planes:
  Learned: 1
  Gomory: 7
  MIR: 6
  Inf proof: 1
  Zero half: 4
  Relax-and-lift: 6

Explored 6 nodes (8776 simplex iterations) in 2.49 seconds
Thread count was 8 (of 8 available processors)

Solution count 7: 174428 174434 174438 ... 2.2683e+06

Optimal solution found (tolerance 1.00e-04)
Best objective 1.744280000000e+05, best bound 1.744121496876e+05, gap 0.0091%

Does anyone have any idea what causes this problem (too large numbers in the distance matrix, rounding errors, ...)? Any help is appreciated!

Best,
Constantin