I found the problem. It’s an issue with permalinks. I turned permalinks off (default) and everything works now. I read on another post here this was a pagination issue which you fixed in 3.0.3 but it seems to have returned I think. Anyhow at least I can still use your plugin now, there really is nothing else out there catering to selling prints as nicely as yours.

I really hope you can find a solution to this so we can use permalinks again but for now I will forge ahead without them.

By the way my permalink structure was simply /%postname%/