Android app freezes after switching apps

I was at sea for some time and tried almost anything. Disabled sensors with no results. Disabled basically everything but the app keeps crashing after switching. Only thing that seems to work is quit the app and open it again. It unfortunately does not ask to send crash data to the developer.

The app crashes only after resuming from background ? It crashes immediately or it first freezes and then crashes ?

We have another user with the same problem and just now we discovered that the culprit is an app called "Force Stop App" installed and activated in Android Accessibility options. Do you have such a thing in Accessibility parameters or any other accessibility setting activated ?