Cloud Storage 'Full' but never used.

Helping a friend- (Windows-PC, Photography Plan 20Gb)

Today they installed Lightroom-mobile on an Android phone. Never before used 'Mobile' or syncing.

They turned on Sync in Lr-Classic, clicked on the Cloud icon,

Immediately Cloud storage says 'Full'  20GB used of 20GB.

Then to trial a sync19 files successfully synced from a new collection in LrC

Only 19 files show in {Lightroom.adobe.com} in a web browser.

{Creative Cloud Files} in a File Browser shows one small file.

? What is going on?  Does anyone have any clues? Why 20GB used of 20GB?