I've had the same problem. It's the custom moves. Some of them don't work with other moves, that I've seen. So, you have to add a custom move one by one to see which one doesn't work with the rest. It's annoying, because some of the custom moves that didn't work for me works on other bending servers, so I'm not entirely sure, but that's the best method on how to solve this.
No problem!
Ok, I got all of the available moves onto my server, but Fissure. For some reason Fissure will not work. All you have to do is move a move into the Abilities folder and /reload the server. Then do /b who. If it shows your username, the move worked. If it says "An internal error occurred while attempting to perform this command" then restart your server and repeat /b who. If it still says the internal error, then the move will not work, which should only be Fissure. Keep repeating this until you do all of them. I hope this helped!