Okaaay… I managed to get this sorted out. It turned out to be the template I was using, it appears spotless is not optimised for this plugin, or vice versa.
I’m not sure on the technical reason, I assume it was the way the page (in my case single.php) was handling the the request being passed in.
I copied the code from the default single.php file and tailored it to the template I was using (Spotless) and it worked great.
Hope this saves others time in the future