Paradise, the symptom acts like the pitch bend is locked to one extreme so that the right hand voices are moved up or down from the tuning center. Disconnecting the pitch bend may not work. The connection needs to be at the center point of the pitch bend variable resistance.
If the above assumption is correct, and if you move the split point all the way to the bottom C, and if you keep the APC setting at basic or fingered, the keys should be in tune across the board but with no rhythm. Selecting the pianist mode would result in the same symptom you are now seeing if APC is on.