I'm setting up my parents' iPad (Retina, 3rd gen, iOS 8) and trying to enable iCloud backup. We've purchased enough iCloud storage space to back up everything, and I use iCloud backup on all my devices without problems so I know how it works. But after starting the initial backup, it goes through "Estimating time remaining" for a while, comes up with an estimate (usually something like 10 or 15 minutes) and then starts increasing the estimate, starting at a few minutes and going up continually until it hits several hours. The progress bar moves to a certain point (about 20%) and just hangs. I've left it sit overnight and in the morning the bar has not moved and the estimate is even higher.
I tried disabling the camera roll (the largest thing being backed up) and it completes. Enabling it and backing up again hangs in the same spot. It seems that the camera roll is causing the hang, but I don't see how to debug it.
I've tried disabling iCloud, rebooting, and reenabling, but that doesn't help. Does anyone have any ideas here?