On another note, I have been having many of the same issues with IntelliLink/Carplay. Very poor QC with this software. Also not being able to flash firmware to the system is a major PIA as well. I too am in the software game, and find it funny that GM thinks this is a mechanics job to fix. That's like asking me to tear down an engine.
I got a hold of a service bulletin from the dealer, all of the issues in this thread are known by GM/Apple. The bulletin mentions all items are related to iOS, and that "Apple is in the process of correcting these issues in a future iOS update", problem with that is, the bulletin is from 9/2015, and there have already been two iOS updates, and no fixes. My bet? This is on the GM side. I have had the problems, specifically the one where the solution is to reset the phone, and it does not work. If there were problems with Apple Car play across the board, it would be in the news. I'm sure there is an SDK for developers to adhere to, provided by Apple, and GM software engineers just aren;t getting it.
Here is the bulletin: