Ah, okay. So this is either your device, or the entertainment system getting confused, most likely.

Some clarifications:

• Car Play features work over wired or Bluetooth, but not WiFi.
• Connecting over WiFi should give you data to your phone, so if that works, it’s doing its job.
• Your phone will use either Bluetooth for audio, or a wired connection for deeper integrations like Maps and such. Car Play doesn’t do data exchange over Bluetooth in that way on either Android or iOS. Some may do contacts or phone control, but not sending streams of data over the WiFi.

So if you want the audio to work AND you want to connect to the hotspot, you’d use either wired USB or BT for the audio portion, and then the Hotspot just gives your phone data.