Say Bob,
Maybe the Korg engineers needed to be sure that there's enough polyphony for the ending they paid so much to program, and the ensemble harmony just eats up too much of it to leave room for the ending voices. You figure - a 4 note chord in the right hand with a 3 note ensemble sound is 12 notes right there - factor in if any of those sounds use more than one partial (tone) per sound and you could easily be using 40-50 (or MORE) notes of polyphony with just your right hand alone.