Library has stopped synching

For years, I have managed my Apple Music library on my Mac but mostly played music using my phone. I would add or delete songs from playlists and that changes would be immediate when I looked at the playlists on my phone. There would be a delay--often overnight--for the play counts of songs played on my phone to appear in the Mac library, but that was not a problem. But for a few weeks now, synching between my Mac and phone has completely stopped. When I delete songs from a playlist they remain there on my phone, etc. I have tried hitting the "update library" command, but nothing works. I have another authorized device, at my office, and I can add/delete items to the playlists there and have the changes show up on my phone, but that is much less convenient. I hope someone has a solution I can try? Many thanks-0