Android software stopped backing up photos

The Android software has stopped backing up new photos on my moto e and moto e 2nd gen but it used to work. I can manually upload but it will not automatically upload.
But it still works on Nexus 7 and Samsung S4. I’ve been through the settings but can’t find anything.
Any ideas why it would stop working on these two devices?

Hi, unless there was a change in the phone itself I do not know why it didn’t work. Have you tried uninstalling and installing the app on the phone?

I think it was due to Android upgrade on the phone. After a few updates of WD app it seems to work again now. I have to go into the app to trigger the backup but that is fine.