Lizzy Firelord

2nd half of issue.

Steps to Reproduce: 

1.  Create a large box

2.  Spawn Baby Villagers in box

3. Spawn Zombie in box

4.  Wait for all Baby Villagers to convert to Baby Zombie Villagers

5. Kill Zombie

6. Spawn Chickens in box

Observed Results: 

No Baby Zombie Villagers will mount chickens.

Expected Results: 

Some Baby Zombie Villagers will mount chickens.

Steps to Reproduce: 

1.  Find Nether Wastes or Crimson biome

2.  Clear all spawnable terrain

3.  Create large spawnable platform

4. Spawn chickens on platform

5. Increase tick speed (optional)

6. Wait

Observed Results: 

No Baby Zombified Piglin Chicken Jockeys will spawn. No Baby Zombified Piglins will mount chickens.

Expected Results: 

Baby Zombified Piglin Chicken Jockeys will spawn periodically. Baby Zombified Piglins will mount chickens periodically.

Can confirm. Mobs which pick up armour still don't always drop it when killed, as of MCPE v1.21.30

it's a known issue for mobs to disappear in Bedrock which I think is a save or load glitch. I've never seen a fix for once the mobs are gone but I heard you can try to prevent it by always logging out out of render distance of any mob you want to keep