When I went to play my MA (pokestadium) I found that the OddJob class was missing from it. I assumed that this was because using OddJob with numerous amounts of people is the only way to exploit my arena. (until the cave spider for the most part.) I went in to play, and I found a piece of netherrack on one end of the arena. It's stuck there, I assumed left accidentally from testing OddJob.
Afterwards, i went to go check other arenas to see if OddJob was removed also. My go-to arena is usually ruins, but to my surprise, for some reason when I joined ruins, it led me to the intaband lobby room, rather than the original ruins lobby. (It still goes to ruins when you start, though.) I'm unsure if this is intentional or not.
(And there's still that glitch with the Knight's potions showing up as water bottles.)