I gave this a try - BIAB 2021, 822, all working fine (well, apart from some of what's being discussed on here).

This is what I did:
- created a track in Cmaj, 4 bars, C only, 3 choruses
- selected a style with 5 instruments _CTRTSEC
- generated, played - all ok
- selected Piano track, changed RT to Best Sub (1855, also 2428) - regenerated and played ok
- for the newly updated track, changed AutoFix Sour Notes to 'Song Chords' - BIAB crashed (not responding)

I tried this a number of times with the same result - BIAB will hang.

I have also tried other RT subs (best Chords,..), sometimes I was able to select 2 or 3 different RTs, generate/play ok, but eventually when disabling/enabling AutoFix Sour Notes, BIAB will hang again..

I hope that this will assist the support team. As far as I can see, BIAB has a problem.....