I'm seeing some strange behavior in summoned Iron Golems. It seemed like the ones I'd summoned/created were being overwhelmed and killed too easily while I wasn't there to see what happened, so I added the Invulnerable data tag to two new summons. One of them has been staring at a patch of grass adjacent a building for a day solid, ignoring zombies that approach him until the sun eventually burns them up. The other just paces an area no longer than 3 blocks despite having the clearance to move, basically spinning in a circle, though he at least attacks enemies that approach him. I know a lot of improvements were made to mob AI, but it seems pretty buggy in Iron Golems at the moment.