Multiple misfires

Has anyone had any issues with this? We have a 2017 GLC43 AMG with less than 16000 miles on it. Bought in Oklahoma then moved to Colorado 6 months later. All has been fine. Just took it on a road trip back to Colorado and had problems 200 miles 3 hours after filling up with premium gas in Colorado at Diamond Shamrock. Was driving 75-80 when the check engine light came on and could not accelerate. The SUV went into limp mode at 40 mph so I was able to get to an off ramp to check things out. Called Mercedes Embrace. They said the car would have to be towed but it would take 5 hrs for the tow truck to arrive. We checked the gas cap. It was tightly sealed but took it off anyway and replaced it. Took it for a test drive and all seemed fine. Drove another 300 miles and it happened again. I pulled off the interstate, turned off the engine, replaced the gas cap and all was good to go. I pulled off an exit that had an O’Reilly’s Auto Parts store and had them check the codes. PO300 multiple misfires showed. PO304 cylinder 4 misfire, PO305 cylinder 5 misfire, PO 306 cylinder 6 misfire. Car seemed to run fine until 30 miles and 1 mile to destination when I had to turn the car off, replace the gas cap. Took it to Mercedes dealer for service under warranty. They pulled up the codes but could find no sensors showing faults etc. they ended up finally just saying bad gas because they couldn’t find other issues, dropped the gas tank, put a cleaner in it and are now going to test drive it for 60 consecutive miles on the highway. I am having the state of Colorado test the gas from the gas station but do not have results back. There was no indication of sediment or water in the gas at the dealer. Mercedes says the repair is not covered under warranty. Also suggested that since it is a finally tuned engine that the change in altitude could affect it.

Has anyone experienced this? All 3 cylinders on one side misfiring? Wouldnt I have had an issue long before 200 miles and 3 hours of driving when the tank was 2/3 full of the newest gas? Seems kind of crazy that Mercedes AMG would have issues changing altitudes and if it did that service would not be covered under warranty.