Make sure you have WIFI Assist enabled, Wireless CarPlay connects your phone the Car WIFI which I don't believe give you internet access.I’m not pulling any data in while connected to CarPlay. Maps are blank, can’t connect to Apple Music, can’t pull in EA or PlugShare maps. Restarting car and rebooting center stack no help. If I turn off WiFi on my iPhone, then Maps, etc all work on my phone.
It’s as if it’s not using the phone for cellular service. I formerly had the Verizon hotspot, but no longer.