For me it also doesn't work. 2.5.5516
It doesn't find back any albums by "Auto-tag by album", though there are many albums in discogs that correspond.
What I noticed is that if I fill in the exact album artist in "album artist" under "Album auto-tagger", namely the one that I found via Firefox on discogs (e.g. "Various" in stead of "Various Artists" or in stead of -empty-), it does find back the album!
So maybe, it's just a matter of not requesting the fields that are manually made empty (after they were filled in on dialog creation)?