Why is this happening?
GM Engineers chose to use a Gel substance to bond the touch glass to the outer plastic on the touch screen.
Sadly, this gel dries out after a couple years and gets hard or evaporates.
With the gel hardened or missing, touches are no longer registered by the system. Sometimes, there is a cracked appearance and random or erratic touch response.
The only permanent fix is to install a gel-free touch screen. Watch the video below to see the issue in HD resolution.