I thought maybe something was wrong with the UC4 to UC5 USB adapter I installed, so as a test, I made up a quick USB stick with MP3s and it recognized it instantly and started playing, so the data portion of the USB port is working. For some reason it just doesn't recognize the phone as a USB device.
If I remove the phone from device manager and connect it via USB, I get a generic "iPhone" listed under devices, but it won't launch carplay. Always wants me to add the device. Was thinking something on the phone might be stopping it, but it worked fine via USB on my old UC4. Might try plugging it in with wifi and bluetooth disabled and see what it does. (EDIT - That didn't make a difference. Next step is to reset the phone software and see what happens.)
The wireless carplay is OK, but the audio quality isn't the greatest, and apple maps is very "jerky" (still for a second, then catches up, over and over).