Denon MC6000 Mk2 CH1 issue.

Erazmus

Using Traktor 3.5 on Denon MC6000 Mk2. With usb input from PC running Win 7. Was working fine until now.

CH.1 volume and associated controls have suddenly stopped working. They work via CH 1 direct audio input but not via USB input so doesn't seem to be the knobs or volume slider.

Have tried updating firmware and reinstalling drivers, but no good. Also tried on another PC and no change. Tried a different usb cable (not Denon) but no good!

Any ideas what could be the issue??