The Bug:

Zombies with their "CanBreakDoors" tag set to "1b" cannot break doors while riding chickens.

Steps to Reproduce:

1. Ensure that the "mobGriefing" gamerule is set to "true" and the difficulty is set to "hard" by using the commands provided below.

   /gamerule mobGriefing true

   /difficulty hard

2. Build the setup as shown in the attachment below. setup.png
3. Summon a zombie riding a chicken on the diamond block that has the ability to break doors by using the command provided below.

   /summon minecraft:chicken ~ ~ ~ {Passengers:[{id:"minecraft:zombie",CanBreakDoors:1b,IsBaby:1b}]}

4. Stand on the other side of the door opposite the zombie.
5. Switch into survival mode and get the zombie to notice your presence, so that it approaches the door.
6. Wait a couple of seconds whilst it stands at the door.
7. Take note as to whether or not zombies with their "CanBreakDoors" tag set to "1b" can break doors while riding chickens.

Observed Behavior:

Zombies cannot break doors while riding chickens.

Expected Behavior:

Zombies would be able to break doors while riding chickens.