One way I addressed this exact situation: Compute a hash on the state after each iteration and save it. Now run again normally and save several iterations worth of state somewhere. When the hash diverges, you have hit the race condition.
Do this a few times until you've characterized what's happening and your brain figures out how and why by seeing the pattern this will (hopefully) reveal.
Do this a few times until you've characterized what's happening and your brain figures out how and why by seeing the pattern this will (hopefully) reveal.