If CarPlay isn't working as you would expect it to, the article below may help::
If you need help with CarPlay – Apple Support
Eg: says:
"Make sure your iPhone has the latest version of iOS."
and
"Check your connection to your CarPlay stereo:
✽. If you have a wired connection, try connecting again with a different USB cable to a different USB port if you have one.
✽. If you have a wireless connection, make sure that Wi-Fi and Bluetooth are enabled under Settings > Wi-Fi and Settings > Bluetooth".
and
"Make sure your CarPlay stereo is using the latest firmware from the car manufacturer. Check your car's manual for more information".
Also:
If you want: check you have set up CarPlay on your iPhone as Apple suggests
Use CarPlay with your iPhone – Apple Support
This article has some tips: Play music and podcasts in your car - Apple Support