[Q] Proximity sensor issue topic

My canvas magnus proximity sensor is not working properly. During calls screen gets blank correctly but the screen not get on automatically after removing phone from rear. It turns on only when either call gets disconnected or i have to press power button to on it.. When i check sensor via proximity sensor app it shows that it is working right.
Strangely of i use custom rom then it's working correctly. But not in stock ROM.
PLS provide some fix.
Thanks in advance