I can confirm that all the folders exist but that completely missed the point: the library is still showing content from folders that have been removed from the library. The problem is not with what is still there
Running scans, emptying waste, cleaning bundles, optimising the database have no effect.
Since this appears to be a longstanding issue (based on other threads from years past) I am in the midst of a complicated Plex Dance to clean out that Library without losing all the metadata belonging to the files in another library.
