In our application sometimes cases are corrupted, it is no longer in sync with the latest assignment and because of this users are not able to continue with the cases.

This always happens after an 4-eye approval step so 2 users are working on the same case at the same time window.  The cases are using pessimistic locking and there are no in between commits. Are there other possible causes explaining this behavior? For example are there known concurrency issues when the same case is updated from 2 different web nodes? Can it happen that the datase is updating the cases in the wrong order?