I can't get my Apple Music or iTunes Match playlists to sync with my iOS devices.

OK, this is a very odd one. I just signed up to Apple Music today but am unable to sync my playlists across devices. I am an iTunes Match subscriber and previously this was working just fine. Now it isn't.

On my Mac, everything works fine. Music downloaded, my playlists and synced up. On my PC iTunes is also fine. Syncs up no problem. The issue is with my iOS and iPadOS devices of which I have 3. None of them will sync my playlists from Music.

The devices are a 2011 iPad Pro, an iPhone 12 Pro Max, and an iPad Air 2.

I have tried the following:

Turn off and on Sync Library

Signed out and back in to iCloud

Reboot device

Hard reboot device

Wipe device and restore from iCloud

Take backup with Mac and then wipe device and restore from Mac.

Every time I end up with a couple of very old playlists but none of my extensive iTunes Match library and none of my other playlists. They just sit there saying Syncing Library (or Loading Library in the case of the iPads).

As a test I installed iTunes on a PC that previously didn't have iTunes on it and tried to sync with iCloud library. It worked. All my music was there. It's just my iOS devices.

Help