iOS 13 screw-up - Songs not syncing On my iPad as well as on my iPhone, after I updated to iOS 13, I started to observe following issues:


The artwork that I had painstakingly added to all my albums was just gone from some. The artwork is present in iTunes (pre-Catalina) and Music app on the Mac but it does not show anymore in iPhone or iPad.
The more sinister one was that some songs were showing on iPad and iPhone, but when I'd click on the song to play it, it would skip and play the next song in the list. If I'd put that one missing song on repeat, nothing would play.


For long time I did not even notice this. It came to surface when I selected a song in CarPlay and the phone started playing the next. Later I realized it was happening with many songs.



What's the fix?
Music/iTunes syncing with iOS devices is indeed slightly screwed. From my diagnosis, it is because of iOS 13 update and has little to nothing to do with macOS Catalina update.



Fix:


Connect your iOS device to Mac.
Go to your device syncing app:


iTunes for pre-Catalina; and,
Finder for macOS Catalina.

Select the device you want to fix your music library on.
Go to the 'Music' tab in the device sync settings.
Uncheck 'Sync Music onto device name'.
Click 'Apply'.
For verification, eject the device and see that there is no song on your device now (except for maybe the content purchased from iTunes Store).
Plug the device back in and check the 'Sync Music onto device name'.
Click 'Apply'.
Wait to let the library sync to your device.


The missing songs should be on your device and the artwork must be restored as well.