CarPlay and Hands-Free Calling

I'm being told by a car stereo manufacturer that part of CarPlay's native functionality is to turn off BlueTooth when connected to wired CarPlay via USB. The issue I'm having, is that when connected to CarPlay, I can't make or receive calls. The incoming call, for example, shows up on the stereo screen, but the phone itself rings. If you press the green answer button on the stereo screen, the call is answered, but there's no audio, either through the cars speakers, or through the iPhone itself. It's the same scenario for outgoing calls. I've tried every which way, and checked every setting to no avail.

The manufacturer said I have to unplug the phone from USB to exit CarPlay, so the hands-free calling will work through BlueTooth. Sounds like a dangerous distraction to me. Imaging you're using maps in an unfamiliar area, you get a call, and have to unplug, lose maps, etc. while driving. I can't imagine anyone would design something like this. My Tacoma has wired CarPlay, and outgoing/incoming calls work fine.

Any advice/input/validation would be most appreciated.