If you have the 8.4” UConnect 4 even without Nav, it has CarPlay and it should work with no worries.
Like you did, I would check the phone settings first.
Then try a different cable (the most likely problem as cheap ones and even apple ones can fail internally). (Just saw
@WRH ’s post, he’s right that well cared for cables rarely fail but in this case I would still suspect the cable).
Then try all the different usb plugs (the ones up front).
Then try resetting UConnect... still unconfirmed how to force the truck to soft reboot, but if you shut the truck down and sleep it will have rebooted overnight.
Then try a UConnect software update, as I
think I saw somewhere you can do from the screen.
... then I would take it in to the dealer.