I also have had this same problem. The first time it happened, truck had 150km. Brought it to the dealer and was told problem was fixed. I was told it was a camshaft sensor. I also told them about the no start long crank issue with the gas jobs and said make sure the ECM is up to date. It did throw an engine light. No start happened again 100km later. Brought the truck back to the dealer. That was on April 13th. Truck is still in the dealer as we speak. They tried a new ECM. Problem persisted. The no start happened in their shop. Then they said they need to pull the cab to get access to the timing cover to look at the timing ring on the camshaft. Also just got a call yesterday saying the GM engineers are coming down to look at the engine. I’ll keep you guys updated. Confirming I have the same problem. Long crank, maybe 20-30 seconds and you can do nothing to stop the crank minus remove the battery terminals. Then it fires right up. For me though, problem was worse after they changed the camshaft sensor and updated the ECU. I have a feeling this is all software related.