@JJJJJJJJ: Are you using an adapter in your car to connect the USB-C cable, or are you able to directly connect it? Despite the cable not having a 'correct way up', you may wish to try turning it 180 degrees to see if this helps. Alternatively, try switching off the phone temporarily to see if you're able to establish a charge.
Could you perhaps try clearing the USBSettings cache and data to see if this helps? You can do this by heading into Settings > Apps > Tap the icon next to 'Your apps' > Show system apps > OK > Search for USBSettings > Storage > Clear cache, then Clear data.
Thank you this solved my USB charging issue.
So the fix you provided worked for a little but it has since stopped working entirely. My phone does not charge via USB anymore, it requires a charger plug at all times. Solution?
It could point to a software issue, but I'm not 100% sure so I'd like you to send in an error report in order for our software engineers to get a closer look at the issue. You can do this by heading into Samsung Members > Get help > Error report. Please send in a report within 15 minutes of the issue occurring, alongside attaching an error log. Once our engineers review this, they'll be able to provide more information.