When you set endermen on fire, they start teleporting crazily, and forget they are aggressive against you.
(If this is a duplicate, sorry, I didn't find something similar)
Linked issues
is duplicated by 2
Comments 3
"Enderman on fire also now behave the way they do when it is raining - they teleport like crazy. I figured Enderman would freak out when on fire and teleport all over the place. I know I would."
Maybe they are teleporting too far away from the player and forget about him/her?
Intended read comments in MC-4253.