I fired up my BK-9 today, and I did what you suggested for Upper1 I kept the same sound in both performance settings, but muted on the other Perf., it worked like a charm. I programmed the performance settings in a sequence, going forward all the time (I use a second sustain pedal for that), it worked very good.

Thank you so much for sharing that info, if I run into this problem again, I'll have a solution.