Reply to S4 Weird problem or me being a knob?

For some reason, and i believe it only happens when messing with the FX section i seem to manage to disable to crossfader?

It still controls traktor but makes no difference to sound output, only way to solve it to restart traktor then its fine.

Tried recalibrating it but doesn't seem to do anything, it must be something im doing as a quick restart and its fine.

Any suggestions