Hi Geez,
It doesn't seem like the "420x" server has been moved as of right now and still exists on the Official public shard. Is this a Bohemia server? Steam provides the server with a map number, while the vast majority of servers show 'dayz_auto'.
Cordially,
Russkie

I see this bug in every round. There is almost always one person who cannot be muted. I think that when the 'map > players' is open you may be able to mute them, but not using the scoreboard[TAB].