Shulker boxes make items dissapear

What I expected to happen was...:
I expect my items to still be in the shulker box after i exit the game and come back again.

What actually happened was...:
the items stay in the shulker box when you place it down and open it, you can destroy it, still full. Leave it on the ground and restart the game, the shulker box no longer stores stuff and all te items have dissapeared

Steps to Reproduce:
1. put the shulker box on the ground full of items
2. exit the game, just the world
3. enter the world again

4.open the shulker box, the items are gone