See: http://forum.xda-developers.com/show...5&postcount=80
tl;dr: after flashing 5.1 factory image (not wiping user data), seems sensors are kaput.

I've cleared cache and restarted, no joy. Restarted into Safe Mode, no joy.

Think I'll have to flash BACK to 4.4.4 again ... as the phone has not had any hard bumps, drops, or other physical problems. Anyone else encountered this??

there are many apps which aren't compatible, like XMOD, Freedom etc.! why?