Brolando

It did have seams around it, so it must have been somewhere outside of the UV space then. Thanks for your help.

I think so, I bought mine on Steam but I'm assuming that's being kept up to date. But yeah that's exactly what I did, but for some reason some of my UV islands just end up being stretched into that corner. I also managed to fix this in 3DS Max, but after exporting it and then trying to import it into 3D coat again the same thing happened, then I tried that same file into Substance painter and it was fine there. In the end I noticed that on the back of my model in the UV room there were a few faces that didn't get the checkered pattern projected onto them, so I ended up removing them since nobody is gonna see that part of the model anyway and after that it worked. Still not sure what caused that though.

Thanks, that worked! I can also just do it in the UV room though.

I think you misunderstood, this is the result in the paint room after I clicked apply UV set.

I was just wondering if there's a way to select an entire stack of identical UV islands after you have stacked them on top of each other.

So I've been trying to unwrap a model and in the UV room the islands look just fine: But if I go into the paint room it looks like this and the result also carries over to other 3D software: