This effects survival mode.

The enderman, when making hostile by looking at or attacking will attack.

But then when he loses interest or teleports away, he then stops trying to attack you. even if you look at him again, or hit him.

I hit an enderman several times and he didnt become hostile towards me again!!!!!!!!!!!!!

Yet, he still teleported to me wherever i went but didn't attack, even when I hit him.

I think this bug is an issue that was caused by the fixing of the bug where an enderman will keep teleporting to you after making him hostile then going into creative.

That bug was fixed in update 1.12.1