In typical Apple form, it seems like the more they update CarPlay, the worse it gets.
Recently, even opening Facebook while I am parked and listening to FM radio or SiriusXM causes the NEX to switch to CarPlay mode and changes the Audio Source to my iPhone.
It's driving me mad!!!
And don't even get me started on the Escort Live app which switches the NEX's source to the iPhone everytime it detects a radar source! (This was previously fixed by turning sound off in the app, but that is no longer working!).