(using MB 3.1.6286)
As seen in the following screenshot, browsing "Artists" will have the wrong track count if an Artist is also a Performer (Charles Mingus in that case). There is only 9 tracks in that playlist, so I'm guessing it counts each instance of the name in the splitter as a different track.
Thanks for all the good work
Edit: I have tried deleting the "Charles Mingus - Artist" line in the splitter but a file rescan will automatically add it back.