Objective criteria "stat.killEntity.Husk" does not work completely, which exists. Kill a husk will add 1 to score "stat.killEntity.Zombie" instead.
There are same issue with "stat.killEntity.Stray" and "stat.killEntity.WitherSkeleton".
I think this is because Husk is defined as a type of zombie, and there isn't really a mob that has a id of "Husk", so do the "Stray" and "Wither Skeleton".
Doesn't exist anymore, considering invalid.