<< However, because F5 works for all bars 1 onwards, and music can be generated in bar 0, I genuinely suggest that F5 should be able to be applied in bar 0 also. After all, it is a valid bar, because the program itself knows it can generate notes in that bar. >>
I completely agree and only said that to mute bar -1- and bar -0- or the following bar -2- not muting is normal behavior.
-0- being a valid bar, yes, commands F5 and other commands should recognize that bar as valid and an update is in order.
My post was to only address the stated issue of the pickup notes in bar -0- and how to silence it by muting or erasing it. Pickup notes in bar -0- is not new and is something that BIAB has accommodated for years. It's previously been addressed from the Audio Editor Window in BIAB or by exporting to and from a DAW. Erasing it in BIAB is fast and easy and takes 5 seconds or less.
Actually, checking further, on my system it is playing a lead-in riff on the last beat of the count-in, not the first beat of bar 1.
I don't know how to mute bar zero