crossbow & shulker

(When I played in 我的世界, Chinese Minecraft,) I used a Crossbow with Piercing to shot a Shulker (when its shell was opened) and the arrow stay on the ground inside the Shulker.

Then, when the Shulker closed and opened its shell again, it hurt.

I tried again in a flat world, then the same thing happened again.

I think it is a bug.