i was used to avoid all troubles with the proximity sensor by setting my FP2 (Android 6.0.1.) that way, that the display automatically turns off during a phonecall. Then I had to deactivate this setting because I had to use some tone menu, and now I can’t find anymore this settings page…
I’m not sure I know what you mean.
The screen turning black during a phone call is the normal setting and it does so if the proximity sensor does at least half of it’s job correctly.
There is a workaround to turn the screen off manually if the proximity sensor doesn’t behave as it should, but that shouldn’t be necessary anymore since you can recalibrate the sensor so it works correctly again.
First clean the screen from the outside then go to settings -> maintenance ->proximity sensor and follow the instructions on the screen.
If that doesn’t fix the issues you have then #disassemble the screen and clean the “proximity sensor window” (picture below) from the inside and calibrate again afterwards.