I have experienced this situation in previous builds as well and it doesn't seem to have been reported. It's not very annoying, but it's present...
The description of my problem is as follows: I select the rating, tempo, mood and occasion of a song (x) that is playing in the now playing tab with auto-DJ switched on. When I double-click on the next song in the row after doing that (not waiting the song finishes playing), this next song (x+1) is selected but it does not play. Double-clicking this song (x+1) again does not make it play. To achieve playback, i have to play the song after that (x+2) for just a second before being able to play the song previous to it (x+1).
I cannot systematically reproduce this issue as there seems to be a time component involved as how far the rated song (x) is being played before I click the next and how quick I click the next after rating the previous.
Here is the debug log: http://pastebin.com/RKSsHN9h. At line 6265 I tagged the song before clicking next.
[1407] Not playing next song in auto DJ mode [#8232]
Moderator: Gurus