Want to add myself to the list of those with frustrating CarPlay problems. I have found that initially, carplay works fine. If I stop at the store, for example, and shut off the truck, it will not work for the remainder of the day; 9 times out of 10. It doesn't matter if i've driven 2 minutes or 2 hours. More often than not, this happens. Like many of the others, I've tried removing, reinstalling, "forgetting", rebooting, restarting truck, etc.... just trying to find a workaround. What I've found is that no matter what, car play is done for the day.
My truck has some other electrical gremlins; specifically with trailers; more specifically, those with brakes. I've found that it will re-detect that a trailer is connected and flash messages about blind sport warning enablements 3-5 times per trip. Something it should only do when you first start the truck after connecting a trailer. Yesterday, on a 200 mile drive, after stopping for gas just a couple miles in, it stopped showing that a trailer was connected.... AND... it never activated my trailers brakes when slowing down. I have the integrated trailer brake controller. Definitely a safety issue.
Sad part about both of these is that I feel like taking a day off work to go to the dealer will result in a dealer message along the lines of: "Unable to replicate the stated problem".