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.
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.