This (from what I can tell) is a bug/glitch on the Minecraft side, not our side... I usually get it during weird teleportations, or when I walk into a space where a block was during a save, then it comes back and I get "stuck." It comes and goes, and usually restarting the client fixes it. :/

 

Several users were getting it at the same time, everyone who wasn't getting it told the others to restart clients, and everyone was. As well, other problems also existed on the server at the time. (Check other recent thread in this section.)