Monsters are attacking me when I'm a RABBIT or a BAT. it should not happen. naturally, monsters don't attack them.
(rabbit, bat, and other)

It's actually not a bug at all.

There was a discussion on this somewhere but I can't find it. The tl;dr was that I'm still debating as to whether this option should be ON or OFF by default (leaning towards ON). I'll most likely look into implementing this in the next update.

It would better be off, in my opinion...

A toggle/config option would be really amazing.
default on would probably be fine for most players. for attacking passive mob players