Intregrex 200 / 640mt pro

I don't have the code at hand now, but first I perform some face contour milling using G12.1 (mill mode), no problem there, and after that some face milling using XY-axis only, in G13.1. However I get movement where both C and Y axis move simultaneously, while C is supposed to remain stationary. Is there some code I have to run besides G13.1?

Thanks for help. This is a true oddball control for me.