Pioneer DMH-W4660NEX No audio on CarPlay when stereo turns on

If you turn on the car, and connect CarPlay, until the stereo is otherwise used, Carplay will not play any audio through the device. If you make a phone call, it will initialize the audio channel and then the audio will play after that, but otherwise you have to turn on the radio or use another audio channel before you can use Carplay for music or podcasts or anything at all. I've tried different phones and have the same problem. The stereo people seem to think this is an issue with the carplay software. Any suggestions? I have already disconnected the phone, forgotten the connection on both ends and then re-paired the phone multiple times. Sometimes, but not always, if the carplay is connected with a usb cable rather than wirelessly it will allow sound to be used without another channel being activated first, but not reliably.