Stuck at whitescreen when starting app with debugger - Android Studio 4.1.2

when I start my android application on a physical device with 'Debug App' runs into a whitescreen and does not proceed.

If I do the same without debugger and attaching it afterwards it works fine.

What I tried:

• disable "allow paralell run"
• clean application and delete .gradle folder
• restart adb
• restart device
• restart android studio

Another thread suggests to disable instant run but I did not found that on Android Studio 4.1.2.

Do you have any suggestions?

I tried everything you guys suggested, but only a clean reinstall worked