I just took my 2016 2500HD Duramax in for the same thing. ( A lot of play in steering) 56,000 miles on it.
Toke it to a local Chevy dealer, they told me they found:
Steering lash adjuster was loose.
Need to adjust steering.
Apply lock tite to adjuster and verify proper operation.
Damage may be present inside gear.
Need to adjust and verify.
?????? Is this right?
It's going to take 8 hours to fix and over $600
Nothing mention about the Digital Steering Assist?
Why wouldn't this be covered under Warranty?