How to create:
So Basically if you use a shulker spawn egg and click on grass(not a grass block) the shulkers will immediately teleport or will stay in the grass
What should happen:
Either the grass should break or the shulker should no teleport and stay on top of the grass instead of in the grass
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We're tracking this issue in MC-130571, so this ticket is being resolved and linked as a duplicate.
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A grass is a non-solid block, and so mobs treat it as air if im not mistaken, and shulkers dont like to float, so it will teleport away. This is not a bug.