I am currently using a Verizon Droid 4 which has recently been updated to JB 4.1.2 (exact version: 98.72.18.XT894.Verizon.en.US).
My phone is not rooted; save the apps, everything is stock.
Every time I use my phone without a Bluetooth hands-free connection, immediately after entering a call, the phone goes dark and I can not "wake" the phone through the normal means (power button).
If I connect a Bluetooth hands-free connection, I can "wake" the phone to end a call, put the phone on mute, etc.
This was never an issue prior to the upgrade. Is this a sensor issue? A hidden setting?
Added note: I am using a screen protector. I removed it and found that once the phone is away from my face the proximity sensor allows for the functionality that was once allowed via a "screen wake".
Did they remove this feature in 4.1.2?
It is perhaps the most annoying thing about using the phone at the moment since the upgrade.