Well, the title pretty much sums it up. I just ran into this a few minutes ago, and thought some of you might know if I've overlooked anything. But I've switched out RealTracks in the past without issues, so I don't really know what's happening with these tracks right now.

I'm running BiaB 64-bit, build 619, on a Win7 platform.

Specifics:
I wanted to switch from BossaBrushes#1 to BossaBrazilAlex. I clicked on BossaBrazilAlex and indicated the variation I wanted, demo'd it, then clicked on OK. The name of the RealDrum track changed to BossaBrazilALex, but it continued to play the BossaBrushes#1 track. I called it up again, indicated BossaBrazilAlex again, just to be sure and all, clicked on OK, but still same thing. So I selected another track -- this time BossaTerryClark -- same thing happened. The name changed to BossaTerryClark in the mixer panel but it continues to play BossaBrushes#1.

I have not tried a RealTrack yet to see if it gets similarly stuck.

How do I unstick this and get it to play what I want?

I've had no problem changing RealTracks or RealDrums in the past, but that was with an earlier version of BiaB.