I've been playing along at home, and have a partial explanation of what's happening.
.... Playing the album now will also queue the tracks alphabetically by title.
Even though the tracklist isn't shown in your view, somehow I think you have accidentally sorted the tracks by a field other than track number and MusicBee is queueing tracks in that order.
It might be a bug, or it might just be an unfortunate side effect of your particular panel configuration.
Hi Zak and thank for explaining about the queueing.
If I select “Music” in the Navigator (bottom left), then:
Following your example of sorting the tracks by title and then playing the album: Yes, that works perfectly. Any sort order that I set in the tracks panel (middle) plays in that order. No problem.
But if I select “Now Playing” in the Navigator, then sort by disc-track, (shows track 1 at the top), then Play Now (on album, left panel): MB reverses the tracks and plays track 16 first.