Screen blanks when making phone call FP2

[paulakreuzer]

Try to clean your proximity sensor and recalibrate it in Settings > Maintenance.

If that doesn’t work please continue here:

Proximity sensor (&Recalibration Tool) not working anymore with Android 6

Since upgrading to Android 6.0 the proximity sensor does not notice when an already approached object is removed. An implication of this issue is the black screen while having a phone conversation leaving you unable to quit a call even when you are still in dialing process. I already tried out the recalibration tool, aswell as cleaning the backside of the display. Strange that this problem has been fixed for Android 5.1 but now seems to occur again.