I'm having the same grinding sound as you do. I own an 2017 A5 but I think and it looks to be the same shifter. That shifter has a little motor in it to put it back into the vertical position if you press the "P" button while in the manual mode ( slightly tilted to the right ). I've been having that noise since I'd guess 20 or 30k km and I'm now at 180k with no issues except that little noise.