CC Bibliothek synchronisierung Fehler

Since the last update of Adobe CC Desktop there is a problem, first showing up as cursor-sandbox is running for about 2 sec, but repeating every 4-5 sec. I tried to find the reason and looked at CreativeCloud App > Properties > Sync: Syncing is shown as actual, but a Error-message is opening for only 1sec (hard to read in that short time: Adobe CC library syncing Fehler - bitte melden Sie sich bei Creative Cloud an). This massage stays for only one sec, but repeating every 4-5 sec!
I tried to close CC, restart cc, Log off CC, rsetart PC, Log-in cc again etc. Nothing changed, neither syncing is active nor inactive.
What can I do?
My System: Windows 10 /64 with Photoshop, Lightroom classic, Lightroom CC, Bridge (Abo)
Uwe Schröder