For Release [r6311887], when I import the tags the tracks, listed as A and B on Discogs, appear as 1 and 2. The titles don't get added at all. In the "adjust tag info" window, they appeared with "TEMP_ title" tags
When I went to "edit release" I found that there were two extra blank tracks, which did not appear in the release as displayed in Discogs. (You can see this in the edit history). I deleted those, and then the release imported correctly.
While this is a data error in Discogs, MP3tag didn't deal with it gracefully.
I suspect similar issues in other problems I've seen lately (I've been doing a LOT of imports from Discogs for 7" discs.)