It took several days to get the battery drain solved on my phone. After taking the update, I did a factory reset and reinstalled everything manually instead of restoring the backup. Most background processes had been disabled through battery saver with exception to those that seemed important or useful. Unfortunately I was still losing charge at an alarming rate. Finally, I disabled the background process for OneDrive yesterday afternoon. Now my battery is a beast! I can't say it will solve your problem, but it solved mine.