Relates to (but does not duplicate) MCPE-61976.

So whenever I try to summon a baby zombie, it spawns an adult zombie instead. I have tried using the short namespaced id for the spawn event (as_baby) and the full one (minecraft:as_baby). Both summon an adult zombie, but it still has a 5% chance of summoning a baby. 

How to reproduce:

1. /summon zombie minecraft:as_baby
2. If a baby zombie spawns, try again and repeat. 

Expected results: A baby zombie spawns every time. 

Observed results: An adult zombie spawns, but there is a 5% chance that a baby zombie spawns.