Resolved in Gurobi v9.1.0: Runtime attribute incorrectly reported as 0

Affected versions: v9.0.0, v9.0.1, v9.0.2, v9.0.3
Resolved in: v9.1.0

Issue

Sometimes the Runtime attribute incorrectly returns 0 after optimizing. This is due to a known issue with calling model.update() or model.write() before querying the Runtime attribute.

Workaround

To obtain the correct runtime, please query the Runtime attribute immediately after the model.optimize() call.