Thanks for the reply David.
I can't see from your screenshots if you have the --runtime=nvidia set. To be honest I wouldn't know where to put it in portainer, without looking it up.
When setting up the container there is a runtime tab (screenshot) I'm guessing this is where I put it but it also defaults to NVIDIA, I'm guessing since I edited the daemon.json file.
Did you read up on the docher hub entry for plex?
Yeah, I have referred to it seems like I have everything covered. It just doesn't seem to work. Must be missing something.