My LG Nexus 4 runs stock Android 4.2.2. I use Bluetooth for phone calls with a one-ear headset (Plantronics M100).
Sometimes I notice in the power toggles menu that Bluetooth has turned OFF and when I go into the BT settings the slider is indeed set to OFF. When I touch the slider, it moves to ON but after a fraction of a second it quickly moves back to OFF.
Sometimes Bluetooth is even reported as ON but it still won't connect to any other BT device. In this state, I can turn BT off and then on again, but it doesn't resolve the problem.
Only a device restart seems to resolve this, so that I can turn BT on again. This happens every other day or so.
Is this a bug in Android? Is there something else interfering? How can I troubleshoot this?