No problem like that with my Ascent. Have you tried different cables and are they "MFi" certified cables? My understanding is that many CarPlay issues are cable related. I've been using Anker PowerLine II 1ft Lightning cables.
I haven't had that issue and I use Amazon music as well. My only issue has been a weird kinda skipping occasionally when I first connect Car Play that goes away after it's been connected a few minutes.
Also second the Anker cables, they are the only other ones besides Apple cables that I've had any luck with.
Sometimes wonky CarPlay behavior is due to a fouled up lightning pot on the phone. I once had connectivity issues and found a lot of lint buildup in the socket. A toothpick works pretty well to clean it out.
Phone is up to date and port is clean.
I'm assuming the music being sent from the phone to the head unit through the USB cable is digital eh? So you either get the data or you don't right? It's not an analog plug. Unless the channels are sent in two streams for left and right (unlikely)