First. Do you have enough tongue weight? IF the TT is lifting the vehicle. I'm betting you don't
Have another question. When you setup your hitch. did you follow the GMC directions on how to setup a air ride vehicle? If not. there is a chance that when you start the vehicle it is rising up, and changing the weight that the WDH transfers. I had to let my TV level itself, and while level. Turn my air ride off so that it won't lower to adjust my air ride vehicle. there is a button some where. You want the TV sitting pretty level BEFORE the air ride levels it.
Next. Your TV tires. Do you air them to max when towing, and are the P tires, or LT.
And then, as you didn't say what TT you have. Is there a chance that you have more Tt than the TV can handle?
Sometimes it takes a lot of work to get it right