This machine is NOT a WK in any way shape or form (I still have a WK-7500). If I was going to take a guess I would say they used the PX-560 OS as both machines overlap in functions. I know I have both!

My MZX has the same issue as Dan's however, I am going to wait for a fix which I hope is soon and hope that no more bugs appear.

Other then the issues listed, it is a great arranger keyboard!
_________________________
Linda F
Casio Privia PX-560 - Korg Micro Arranger - Casio MZ X500