I have the same issue (and more, see below) with both X10 III and XA2 Ultra runnning OS 4.4.0.68. There is no request for entering the pairing code (which in case of my car kit is hardcoded “1234” which needs to be entered on the phone during the pairing process). The only solution is to use bluetoothctl which does request to enter the code, and so it results in successful pairing.
But even after successful pairing using bluetoothctl (the phone appears on the car kit’s list of paired devices), the phone cannot establish a successful connection with the car kit. There are connection attempts but they get dropped. Please see my bug report for details: