This outfit has a different string length of "core" and "physics".
Just replacing the strings results in a change in the total number of characters in the UPK and the game client doesn't like it.
I've already explained how to get around this here:
Something told me this would happen, really hoped it wouldn't. It seems they are changing the costume code to 4 making it impossible to change outfits. I'm not sure if you can still change the outfit using the old fashioned way i'll try later but this really is a problem.