Easy solution might be to erase all sysex. There’s a parameter in the sequencer when you start a track from scratch that decides if it’s recording the Style track or KBD Part. Can’t remember what it’s called (away from my computer atm) but that might solve the problem.

I only sequence on a computer, so I'm not that familiar with the issue, but I do vaguely remember the issue a long time ago. When I get back to my computer I’ll look at the manual and see if it jogs my memory. There’s definitely some weirdness in the way the BK9 deals with trying to deal with a 16 channel SMF and still have 5 more channels left over for KBD Parts and the Melody Intelligence. It involves a sysex header if I remember.

I used to use the sequencer to record a style, then import the saved SMF into my DAW. I think I solved the issue by simply erasing all sysex, but that sometimes lost some drum editing. I simply recreated the edits if needed when I reimported the SMF to the BK9.

Wish I could help more, but that might give you the area to concentrate on.