Had my 920 since the day it came out and I dont make that many calls with it so i didn't really experience the issue enough to realize I was having it until tonight. Basically whenever I make a phone call the screen is black and stays black until the person i am talking to hangs up. If i hit my side button to get the screen to come back up it will flash for only half a second but then go back to black.
I know it shouldnt be like this because on my old Focus i used to be able to surf the internet or text while i was on a phone call. With this 920 I cannot even hang up on someone or any of the other options available, is this a known issue? Should I just bring the phone into AT&T and have them try and solve it or is there an easy fix on my end to get it straightened out?
I would do a restart of the phone and see if it still does it. If so then either do a hard reset (factory wipe) and try again, or take it back. Maybe a sensor issue when in phone calls if not a little software bug.
I'm actually having this issue as well - unfortunately restarting the phone hasn't worked for me; I imagine it's a software bug based on this issue existing on WP7 as well. I'm going to reach out to both Nokia and Microsoft for information; if I get any useful responses, I'll post back here.
Don't know if this applies, but I noticed it mentioned on Nokia's website that some screen protectors will not allow the proximity sensor (the one that blacks out the screen when you hold it to your face) to operate properly.