I had it and it was corrected with one trip to the dealers service department where I had excellent treatment from end to end and the problem was gone.
In my opinion, this is no different than any other item that would come up under warranty, take it to the dealer and get it fixed. No different than you would do if an injector was partially working or the wiper motor was not working properly. Don't get me wrong, I would prefer that every vehicle I have ever purchased would have been absolutely perfect from day one, the reality is that sometimes adjustments need to be made.
It appears that many of the people commenting on this topic have a poor dealer/service department or just haven't taken their truck in. This is not unique to the Twins, it applies to any of the GM products with 8L90 and 8L45 Automatic Transmission (RPOs M5U, M5T, M5N, M5X), including the Twins, most Cadillac's and Sierra/Silverado, Yukon and Escalade and goes back to 2015.
To me the tranny issue was a lot more minor than the 4 vehicles that had to have airbags replaced, the 3 that had to have ignition switches replaced (one that broke and waited 2 weeks for parts), one that had a bad highlight switch. My favorite one was the highlights would just turn off going down the road in the dark. This happened when I was going from Tok, AK to Anchorage, AK, I don't remember the exact distance, but it is around a 8 hour drive. According to Chrysler it was caused by the headlight switch overheating - that's a comfort feeling. I ended up staying two extra days in Anchorage awaiting parts.
The tranny shutter was an inconvenience, but wasn't dangerous and didn't leave me stranded, so I am not going to be overly critical about it.
2017 Colorado Z71, Cajun Red, Crew Cab, Bose, Nav, Factory Bedliner
Mods: Westin HDX Xtreme Boards, Window Tint, Exhaust Extension, Bully Hitch Step, WeatherTech Mud Flaps, Tuxedo Titanium Tonneau, Bedrug, Box Lights, AeroSkin II
LEDs: OPT7 FluxBeam Headlights, JDMAstar Fogs, JDMAstar Backup, JDMAster License, JDMAstar Brake