It's not just pick-up notes that are affected. If you create a song in BIAB with a melody then decide that a certain bar needs to be 2/4 instead of 4/4, the regeneration of chords will be correct but the melody will be displaced by 2 beats from that point. As Rocket.123 suggests, my workaround for this is to export the melody into RealBand for editing, the import back into BIAB.

Vintage