I dunno I think it can be fixed, I think there is some kind of latch or osmething that could be ground down or removed so the window doesnt catch on it and rolls completely down, Im just hesitant before I rip my whole door panels off
The only thing that can be removed is the rubber stop at the bottom of the door, and that will only allow the glass to roll down another inch or so.
The door is in the way of the window going down any further.
If you've seen them all the way down then you were looking at a Yukon XL, the XL has a "square" door and is wider at the bottom, because the truck is a foot longer.