Too many source folders

I have been seeing this message, ‘Too many source folders. Sync may be stopped’ for about a week. I checked my vaults and only saw the expected source folders: Photos [a copy of my photos from a NAS] and Inbox [from Android].

Today, I checked again and saw 398 folders trying to sync; many of them documents and not images. I did not add these folders to the source! Mylio seems to be duplicating a folder tree of documents.

Is there a quicker way than removing each of the unwanted folders, now showing under Source Folders?
Is there a way to stop Mylio from syncing?