When running a standard looping/fill/transition song and with both on board buttons of BB2 in master control mode, the right hand button label says “transition” while the song is playing but it’s actual action is “fill”. When paused, both labels say “fill”. Doesn’t really affect playback, i.e. both buttons still do a fill and you still have to hold either one for “transition”, just the label is wrong.
(I’m currently using the double master button as I’m worried about accidentally tapping the wrong button while at the mic and playing guitar…once muscle memory of using the one big pedal on BB1 gets better trained, I’ll probably let button two do something else. I also use a Boss FS-7 footswitch and it behaves properly with pause stop previous and next song.)