I came across a weird bug in Artrage 5, when I'm making a stencil, If I accidently name it the same as something else in the collection - it won't add to the collection afterwards even if I change the name and try 100 times. It will completely ignore it making you think it's impossible to add to the collection. Even if you change folders ,it will not matter. the only way around that I found is if I add to the collection as Untitled the default, then I can rename after the fact.

I'm not 100% positive that is what is causing it but it keeps happening when I notice I name it the same as something else the first time.