And you're sure you put it in the correct folders?
Could you please save & close your game, then go back in and see if it is there? There have been instances when the editor would not recognize new resources straight away. This has been logged for fixing.
I'm also having this problem. I went into the files and made it so it should be located right in between "Bat" and "Assassin", but it isn't there. I tried saving and quitting out of the software, which is what I usually need to do when putting something new into any of my project's folders, but it didn't work. Has anyone found a fix?