Takes longer to solve in new version primary due to items now not finding a solution in presolve

Forwarded from our development team:
While upgrading from Symphony version 5.6.14 to version 5.6.17 we are seeing some strange behavior on both our linux and windows builds. The examples below were generated using the windows build but we are seeing similar behavior on linux as well. We have a small test case with 2,278 rows and also 2,278 constraints (LPT file attached in scenario.zip).

On version 5.6.14, this case solves almost immediately. On version 5.6.17, the case takes 2 to 2.5 minutes to solve. The output logs with verbosity level = 50 are attached. The default settings are being used (do_primal_heuristic=1, prep_level=5) and we have first feasible activated.

The runs are similar until it gets to the "Now displaying final relaxed solution..." message. The old version finds the solution right away using heuristics while the new version goes into iterations. So far, only this test scenario is showing the issue. -Bill

Start with the attached scenario.zip LPT test case and the verbosity-50 output logs. Reproduce the case on SYMPHONY 5.6.14 and 5.6.17 with the stated default settings, then compare behavior around “Now displaying final relaxed solution...” and first-feasible handling. Done means the regression is identified and the test case no longer takes 2–2.5 minutes in the newer version.

Written by the indexing model from the issue text.