Problem with importing album art images

Sorry if this has been already asked… i cannot solve this.
scenario: boxset with 2 or more CDs, each containing its own album art folder with this structure:

in this scenario, roon ignores image files contained in the ART folders, even when the CDs are not identified with a single boxset but with different CDs

On the other hane, if the name folders were:
every CD would get its own albumart.
My problem is that if i change the folder names nothing happens. I’ve tried to:
-change the names of the folders
-delete completely the folders, clean the library and then import again the folders with changed names
but no matter what i do, roon recognizes the files, remembers the first structure, and does not scan the ART subfolders.
I canno find a solution
Any suggestion?