Proximity Sensor Related Issue
Proximity sensor: During a call, the screen still stays on and doesn't turn off automatically, or the screen does not light up during an incoming call.
Solutions:
1. Install "sensor list" app to check whether Proximity sensor works or not: https://play.google.com/store/apps/details?id=com.miian.android.sensors&hl=en
2. Please try to clear the cache, back up all the data and flash to the latest OS version.