Ok, so I have been asking around a few times now, and nobody answered so I'll try here.
I recently found myself a nice dungeon, which I turned into a XP farm. Now the problem is, yesterday the mobspawner spawned zombies. Then, after a while (no changes were made in the area, no extra light or anything) it stopped. It hasn't spawned anything ever since.
What's up with the spawning? Is it off? Is it bugged? Are XP-farms against any rules?
Thanks in advance!
-Remonius