I have BIAB Ultrapak 2018 for Windows.

With regard to the part maker, twice recently i have been able to get parts C and D to appear with consecutive mouse clicks, but when I finish the song and generate the tracks, parts C and D disappear and things revert to A and B as the norm.

I have been unsuccessful in finding any written help in the manual to describe how to set and maintain parts C and D.

Can anyone point me in the right direction?