Upon summoning a mannequin on top of a happy ghast the technical entity falls.
Normally when a player is standing on top of a happy ghast, it freezes and his top hitbox become solid. However, this behavior does not happen with a mannequin (that should be an entity that behave like a player)
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After consideration, the issue is being closed as Working as Intended.
Please note, that mechanics of the game may change between updates.
Things such as graphics, sounds, world creation, biomes, redstone, villagers, and animals may not work the same in current versions.
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