Same here. UT 15.04 OTA-3 on a Nexus 5 is now my only working phone. I haven't had this happen to me yet.
If nothing else works, possibly just a re-install of the image? I had bugs with my sim card that went away completely after my 2nd install. It's been bothering me, but I honestly have no clue what/if I did anything differently the 2nd time around.
I guess repeating tasks with expectation of different results pays off for some of us... 😉
The issue hasn't returned since.