I just purchased a 2021 Tucson Hybrid Limited and I can't get the car to recognize the Iphone over the cable.It is an RF issue along with the connectivity. There are certain spots within my commute where I know for a fact that the apple car play will cease to work. It happens every time, but the reconnection after passing these points is hardly ever.
We have the 10 inch display and the specs say that Carplay only works over the cable, not via bluetooth. That might be an advantage if the problem with interference is an issue. We used the cable that came with the XR phone. It does not seem to recognize it at all when trying to do the setup. Hope someone else has figured out how to do it.