Bob,
Closed my browser...same result
Opened a tune with no tempo changes... same result.
This will drive me nuts unless a fix is found. I use this technique ALL THE TIME and now I can't.
My temporary work-around is to generate the same track on another track, do the regen (still erases stuff)... then cut and paste a bar / phrase back into my original track... BUT this is not an acceptable solution IMHO.