I have the same problem. Could you please give me an answer?
Hi guyys, I think you are not allone. I was on CM11 Rom (LBL) for over a year - two month ago I flashed CM12 for the first time. Now the troubles begin:
Because CM12 especially 5.0 over all is still a problem (wifi, calls etc.) even for their own Nexus series.
Anyway, I had a perfect backup of CM11 and I had perfect backup of the currently running CM12 Rom.
Because I need a stable running Rom for my bisiness, I switched always again back to my CM11 Rom.
But some day last week I flashed back to CM11 and was in a full bootloop. No chance to go back to Recovery or anything else.
Reason: I don´t know why, but there is something in the scripts of Kitkat or Lollipop, that damages SD cards, when you often switsch between the two systems. The sd card was dead, only readable, but not writeable again!!!
So in the latest backup I made to the sd card, not all data have been written on it (not a complete backup) and when i tried to restore the system, with CWM, only parts of the recovery were readable. Hehe, bootloop. **** happens
I personally think, that is a problem since Kitkat. Google allowed only verified apps to write on SD-card. I assume, that there is a problem in the scripts.
My tip: Save your time with experiments - install your phone from beginning with .ftf file. I did it too
Greets, reinipic