Hello! I was about to create a new post for this issue, and found your post.
So far, NOTHING has helped me. I also have a very large Music Library, and have tried a number of things.
I initially tried an iPhone 12 Pro to iPhone 14 Pro Max direct phone transfer on Friday, but that whole thing failed, and I had to restore from an iCloud backup. After I was finally able to start using my phone is when I noticed this issue.
Since then I’ve tried restoring the iPhone 14 Pro Max five times! Five. Including trying iOS 16.0.1 and the two recent 16.1 betas. I’ve also tried setting the phone up as new! No change. I’ve even tried disabling syncing my Music Library in Settings and rebooting, and tried disabling syncing my Music Library in Settings and then deleted the Music app (!) and waiting to reinstall & try again until the next morning. No change.
In all cases it still loads almost all of my Library, up until maybe it’s state about 2 weeks ago or so, and then the “Syncing Your Library” progress bar box at the top disappears. After a few moments it seems to try again, rinse and repeat. If I try adding anything to my Library on my 14 Pro Max, it’s not reflected on my other devices.
Meanwhile, adding any music on my iPad Pro, M1 MBP, Intel Mac mini, my Wife’s iPhone 12 Pro, or even my Daughter’s iPad Mini 6—- everything shows up as expected and quite quickly. All these other devices are on different OS versions, too: iOS 16, iPadOS 15.7, iPadOS 16.1 b9, the latest Ventura Beta, and macos 12.6.
I’ve filed Feedback with Apple in case anyone happens to see this, but I’ve lost hope at this point until they can try addressing this thru an update.
FB11541646