Small entities clip through upright open shulker boxes

When a small entity is standing on an upright shulker box and the shulker box is opened, the entity falls through the shulker box.

How to reproduce:

1. Place an upright shulker box.
2. Stand on it.
3. Execute the following command:

   /attribute @s minecraft:scale base set 0.0625

4. Open the shulker box.
   → You fall through the shulker box.
5. Summon a baby turtle on top of the shulker box by executing the following command:

   /summon minecraft:turtle ~ ~ ~ {ForcedAge:-32767,Age:-32767}

6. Open the shulker box.
   → The turtle falls through the shulker box.

Expected result:

Entities would not be able to clip through shulker boxes.

Observed result:

Small entities can clip through open, upright shulker boxes.