I'm not sure if related but after installing this and got a call, I couldn't anwser it because my screen was blank black. I swiped from top and that stopped the ringing.

Another maybe related problem which occurred in YTPlayer. Sound was coming from the top/call speaker and switching the app on/off didn't work.
Anyway thanks

e: happens in every native and android app, deleting the prox speaker app didn't help.
e2: restarting the phone after uninstalling fixed it, no Prox speaker tho.