If you like some granular control over synced accounts, you probably ran into a little roadblock with Android 5.0. If you wanted to manually sync items in one of your accounts, the button to do that was missing. Well, at least, sort of. In its place was “cancel sync,” even though there was nothing to cancel. That should have only been present after initiating a sync manually with the “sync now” option.
Android 5.1 Fixes Manual Sync Option In Settings, Now You Can Actually Do It was written by the awesome team at Android Police.