So I havent brought mine to the shop yet but I've been having issues with the remote start as well on my 2019 Yukon Denali. It will work great for a while and then all of a sudden stop working. The weird part is that the Lock/Unlock features continue to work but I can't remote start it. When it first started happening, I switched to the other key fob until it eventually started happening with that one also. I hope to go to the dealer in the next few days.