Question:
Is your Tahoe running as you hook up?
I'm dealing with a similar situation with a 2015 suburban.
It seems that if these vehicles are running, the auto leveling system kicks in and cancels the WD effectively removing weight from the front and causing the trailer to ride hi on the tounge.
My suggestion is to follow the GM instructions regarding the auto leveler and WD hitch. Back up to the trailer, then turn off the. While until the WD has you level and distributed properly. Then turn the Tahoe on again. The auto leveler won't need to do anything and your hitch should be working properly.
Please let me know how it goes. My rigs at the dealer until next week and can't investigate this in person. But I'll tell you, the auto level can create a scary towing situation with the WD if not configured properly.