I am dismayed by this but cannot remember the chain of events that got us here. What changed and when, and did it ever work correctly?

I don’t think Force Accidental has always been available, though it goes way back (decades, I think). Likewise enharmonic notation has been improved with E# and B#, Fb and Cb, but this was added not that many years ago.

It seems to me that the most important error here is in the inability for a manual change to ‘stick’. Then it would be nice to explain why in the Dzjang example the A# appears at all. As far as I can remember, BIAB has always done this on occasion (thus the need for the Force Accidental function to be added). But again, I’m not positive about the history of any of this. I think if anyone knows, it could be useful in tracking down what’s happening here.

Again: what changed and when, and did it ever work correctly?

Perhaps one of you could post an offending song, and someone from PG Music could test on earlier versions of BIAB. A few users can do this kind of testing also; I’m pretty sure John Ford can run versions from years ago.

BIAB 2025 Win Audiophile. Software: Studio One 7 Pro, Swam horns, Acoustica-7, Notion 6, Song Master Pro, Win 11 Home. Hardware: Intel i9, 32 Gb; Roland Integra-7, Presonus 192 & Faderport 8, Royer 121, Adam Sub8 & Neumann 120 monitors.