I often see how users, including myself, have said that sync is wonky or doesn’t work. However, I think I figured out why this seems to happen. If one opens the plex app on their iOS device and simply leaves it open for a few hours, or overnight, i’ve never had a sync fail, no matter how much content. So perhaps it would be good idea to display a message to users within the sync management page on a trips and tricks? I know there is only so much the plex app can do in the background before it is shutdown by the OS.
2021 clean-up: obsolete (Mobile Sync is about to be replace by Downloads which handle this differently)