XPS 9320 - Flickering black screen when on power

I've just done a system restore and run the dell support app to make sure everything is up to date.

I've now got an annoying issue whereby if I plug the power cable in the screen just continually flickers black.

I've checked the cable and plugged it into my phone and another laptop and that seems to charge fine.

The laptop has two USB-C ports, one on the left and the other on the right.  I usually use the one on the left, so i'd try the one on the right just to rule out an issue with the port, again the screen starts constantly going black and then occasionally displaying.

 Disconnecting the cable solves the issue.

I've looked at the power options and nothing out of the ordinary for when plugged in and not plugged in.

Any ideas ??

Thanks