Tiptronic Buttons Function Erratic
 

Have an issue with the Tiptronic buttons on the Steering Wheel...

Occured twice in past 4 months and again tonight....
I have been using this mode for past 2 months.... fully functional.

In Tiptronic mode the buttons don't function.....

Neither in D or S..... but changes are smooth and no other evident issues...

Any advice would be appreciated. +++

Slip ring maybe?