New MIMix2s | 9.10.17 - When calling proximity sensor doesn't black out screen

[betaHydri]

When I'm calling the proximity sensor doesn't seems to work well. The display is kept always on.
Then during calling when I press the power button to switch off the display , I can't hear the other party anymore.

 

[betaHydri]

The the test of the proximity sensor is always 5.0.
You can go into test mode via: * # * # 64663 # * # *