Not a bug

the server should ignore empty folders

Are Finstad 5 years ago updated by Tom 4 years ago 4
the server should ignore the folder if its empty (say if you delete a cbz file in ComicRack for example and that is placed inside a sorted folder. the folder will stay for the series even tho there is no files there.

rescanning the library should detect it, it should not care if there is empty folders in the library and def not display them either (just an issue if a series is either deleted entirely or moved to another folder) 

if there is remaining folders from entries that is now deleted it should be ignored, simple as that IMO.
Under review
Ubooquity already has an option to hide empty folders. Check the "advanced" settings section.

Enabling the option "Hide empty folders" does not apply to OPDS feeds. It does work for the web based browser. Is this intentional? Thanks!

No, that's a bug.

Thanks for reporting it.