For what it's worth I'm almost completely sure it only works for elves because I could attune to it if I sat long enough with it. But that's like taking something that isn't mine. And besides, I like my own things and I'd need to let one of those go to attune to this. Of course what I'm sure of flies out the window completely if someone else who isn't elven can attune to it. Have we... tried that?
Anyhow, if that's the problem then we've got to make you elven again, and that's what I just... still don't know how to do. You generally can't fool magic like this, but what's one more thing in a sea of things that haven't worked yet?