Shift knob would not move in Steptronic mode
 

A bit embarrassing that I have had this car for a couple of months and only now actually tried a "sport mode". It didn't take me far, as I found out that the shift knob would not move either up or down when pushed to the left.

The S indicator on the dashboard turns on along with the "1", the car moves, but only in first gear obviously. I tired a bit of force but the knob is stuck solid. Where should I start looking first?

Thanks!