some album covers are no longer displayed (although the cover.jpg/png files are still present in the respective folders).
A "File rescan" of those albums retrieves the album covers, which are forgotten again after MB restart.
Version concerned: 3.5.8206 P
Last functioning version: 3.5.8167 P
The impacted albums are always the same when switching from v3.5.8167 to v3.5.8206.
Cover formats: JPG, or PNG
Music formats: OGG, FLAC, or M4A with CUE
Strangely enough, when copying one of those "vanishing" covers to the folder of another album (having a correct cover display in v3.5.8206), the cover display remains correct for that album.