You aren't the only one who's mcmmo stats aren't showing up, i have a friend who's unarmed skill is almost 600 and he doesn't show up on /mctop unarmed, he says when he does /mcrank everything says unranked. I don't know anything more about this issue, what causes it, or how to resolve it, sorry.
Ever since I bought admin, my /mcrank stopped working. I don't show up on any /mctop even though I was for awhile in the top for a few things. This is mainly why i stopped playing prison