Apple Music icloud sync does not sync to iOS

I'm a happy user of Apple Music. But -unfortunately- the last couple of days the sync to iOS devices is broken. So this is what I see:

• I add a new album, song, whatever on my Mac to my Apple Music library
• I see this song being synced, because on https://music.apple.com/ the changes are also visible
• Unfortunately I don't see the changes being propagated to my iOS devices

I can fix this by switching off the icloud music library sync on my iPhone and re-enable it, but that is not the way to go.

[Edited by Moderator]