Absolutely, I did it.
I tried get out of that server and joining another server.

And I also use this command first when rabbit is disappeared - '/spectate on' and '/spectate off'

But sometimes it does help, and sometimes are not..(I really want to know about when and how is disappear and appear again.)

Really maybe you're right. maybe it is just someone's spiteful joke..(then, why only JJ2+ have the problem? TSF and other version is never have the problem like this.. that is a big mystery..I think there's a spy among us..Help me! I don't wanna die!)