Apple Music Sync Library Stuck

The solution offered by Mario49 does not fix anything. I have the same problem - iOS up to date. I restarted sync, force restarted device and reset the device/recorverd from backup. Nothing did the trick.

Hello mattybonthebeat,

Thank you for reaching out to Apple Support Communities, and we'll be happy to help in any way we can. We understand you're having issues with syncing your Apple Music Library and other files. When you add a new song, syncing again is expected. Does restarting your device help sync the new additions? This simple step can resolve a multitude of issues: Restart your iPhone - Apple Support

"How to restart your iPhone X, 11, 12, or 13

1. Press and hold either volume button and the side button until the power-off slider appears.
2. 
3. Drag the slider, then wait 30 seconds for your device to turn off. If your device is frozen or unresponsive, force restart your device.
4. To turn your device back on, press and hold the side button (on the right side of your iPhone) until you see the Apple logo."

If the issue persists, does your iPhone need updating to iOS 15.6.1? If so, do you have a recent backup for the data in your iPhone in iCloud or your computer? If not, we recommend that you create one as described here: How to back up your iPhone, iPad, and iPod touch - Apple Support

Then update your iOS as outlined here: Update your iPhone, iPad, or iPod touch - Apple Support

We hope this helps.

Cheers!