CarPlay issue with low/no sound coming from one side of vehicle

I plugged my iPhone X into my 2018 Mitsubishi Triton (NZ) and noticed the sound was very quiet on my stereo while using CarPlay when it is on its normal volume setting i have it on.

I checked the balance and fade setting and i moved it to the left side and the front and back speakers worked fine. i moved the settings to the right and i could faintly here a little sound. I thought the speakers were broken, but i did a factory speaker test via the audio unit and the speakers all work perfectly.

I then unplugged the phone and tried the stereo on a FM station and the sound was perfect both left and right, front and back.

I tried using my phone via bluetooth and encountered the same issue as when it was plugged in via cable on CarPlay. I reset my phone and reset my audio unit and it made no difference. I went to a Mitsubishi dealership and had a technician look at it and he couldn't understand why it was doing it either. Finally we tried a Samsung phone and there was no issue via cable or bluetooth.

There is obviously no issues with the vehicle's audio unit and as i have eliminated all elements that it could be the unit by trying another brand phone and all the factory tests and resets

There seems to be a bug in the latest iOS update version 12.3.1 for the CarPlay feature.

Apple please can you address this issue, or if anyone is experiencing this issue... any ideas on how to fix it? if it is at all possible