Steps to reproduce:
- Let a Zombie drown to get a Drowned Chicken Rider
- Try to hit it - no effect
- Stay in front of it - it won't attack
- Screenshot attached
- The Drowner wasn't spawned by Egg or by Command, it was a "regular drowned Zombie"
- The Drowner was at night converted from a Zombie by pushing the Zombie ito the sea
- Meanwhile it was daytime and raining
- The rider didn't do anything special except having the usual chicken idle movement.