The first thing that I would try is to disable the Contour Enable setting.
It may also be that your crossfader isn't closing correctly, so try setting the "Fader cut-in" to 5%, or 10%, and see if this helps at all.
If it's still not working - can you check the MIDI mapping for the crossfader? If this is currently mapped, then please delete all exisiting mappings. It probably doesn't need any MIDI mapping if User External Controller Crossfader is being used.