Shulker Boxes placed in world lose inventory when loading the world

Shulker Boxes that are placed in the world are empty when loading the game, even though they had contents before Saving and Quitting.

Steps to replicate:

1. Place shulker box on ground

2. Place items into shulker box inventory

3. Save and Quit

4. Load into world

5. Shulker box is now empty