The problem was I changed my certificate. If you are authenticated and you change your certificate (even unknowingly) you will get a mismatch problem and be prevented from logging into the server.
If this problem persists you can log-into the server with a different username than what any authenticated user is using.
If you need to get access to your old username, I believe that would require an admin to mumble to remove your previous certification, and become re-certified. But, I'm sure some evidence to the fact that is your username on mumble would be required.