I was trying to cache a zombie for a farm. Named it with a nametag, checked that it has a helmet, caught it in a boat. After that I slept (nearby) and went for supplies to transport the zombie. When I came back the boat was empty.

What I expected to happen was:
Zombie sitting in a boat.

What actually happened was:
The boat was empty, no drop around, zombie despawned

Steps to Reproduce:
1. Wait for night
2. Find a zombie with helmet or one that would pick up items
3. Name that zombie using a nametag
4. Check that zombie has a helmet
5. Catch the zombie using boat or minecart
6. Sleep for day to come
7. Move 2-3 chunks away
8. Come back to see zombie disappear