Problems and issues can arise when using the My Cloud app to auto-backup and update photos and videos from iPhone and iPad Camera Rolls.
So, this post is intended to help prevent the following BIG problem from happening before you begin, or let you know why you had the problem, so you can prevent it from happening again.
IMPORTANT: for very large uploads (such as with a very full iOS Camera Roll,) the iPhone/iPad's Auto-Lock control needs to be set at a high value (meaning, set it to Never,) BEFORE the upload begins, or else the iPhone or Pad's Auto-Lock feature will most likely time out, step in, and shut down the
iPhone/iPad. If this happens, your uploading will stop before it completes.
(WD Support says Auto-Lock is a battery-saving design feature of iOS devices.)
Also, for any large uploads, have a fully charged iOS device, and keep My Cloud app in the foreground during uploading.
Be sure when all is completely finished to put your Auto-Lock control back to where you had it set (likely at 5 minutes or less).
Subsequent auto-backups may not require resetting Auto-Lock to Never if only a few items are uploaded each time.
Yes, it is an inconvenience, but let's "thank" Apple and not blame WD.
I have been told by WD Support that Android devices do not have this issue.