Sudden no sync

—Update—
I logged of and onto iCloud on two of my machine. This reestablished a sync between the two. Will try on the third device now

Morning!

Suddenly I my three devices don’t sync anymore.
(iOS phone and iPad and MacOS)
Native apple iCloud syncs DO take place.

What did I do trying to solve
Backup/export library to HD
Delete iOS apps
Delete macOS
Delete iCloud backup
Waited about an hour

Reinstalled iOS apps (come with a prefilled library of the 50 standard songs and helpers)
Reinstalled the macOS app. Which strangely reinstalled with the old library

Repeated the entire procedure but now emptied the library on macOS. Deleted all songs and empty playlists.

Reinstalled all apps
Switched on iCloud sync in settings on all three devices.
Syncs seem to get processed.
Waited for a while.

- standard 50 do not appear in macOS
- created new song on every device. But neither of them sync

Also importing the library (4667 songs and about 60 playlists) to either the devices does not sync.
Import a specific playlist does not sync

What else can I do?

Hoping to hear,

Jan