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:
Place shulker box on ground
Place items into shulker box inventory
Save and Quit
Load into world
Shulker box is now empty
Thank goodness this is fixed... I lost like 5 shulker box's contents due to this bug on my survival.