Showing Part in Display causes the part to detune

[D R]

Hi...I'm running Cakewalk and playing midi files from it. Some are routed through a midi matrix.

I have ROrgan2 set up to play on Part 4 (midi channel 6). If I press "Part" in the play mode menu and any part is displayed except part 4, it all plays fine and in tune. However, if I go to part 4, it immediately detunes that part....

I'm aware that the actual keys on this U20 are shot..I only use the keyboard as a module and it's possible that the pitch bend is shot too...although this makes me wonder why it only happens on part 4/channel 6.

Any ideas?? there are no pitch bend or wheel commands on channel 6 in the midi file...

TIA