Black screen with universal GUI on Android

I am starting the Universal GUI (2023.2.11.0.0) on Android (android versie 13) with a firefox browser (version 119.0.1).

Login as a user and do my thing. Continue with other work. Phone turns into lock. Want to continue on my phone. Unlock it and the universal gui pops up, but it shows a black screen (mostly, sometimes white).

Only solution is killing the application and start this again.

How to fix the black screen situation?

Addition on the topic. Chrome doesn't give a black or white screen hang. In chrome we see a hang situation, visible by continous turning of the refresh button. Firefox a black or white screen (hang situation)

Also happening in the latest GUI version 2023.3.11.0.0

Does anyone recognize this behavior?