Shulker Boxes won't keep items

Shulker boxes aren't shulking right now...

What I expected to happen was...:

Shulker boxes doing as intended.

What actually happened was...:
Instead they act as if they are normal chests.

Steps to Reproduce:
1. Place down a shulker box (either with existing items inside or to place items inside)

2. Break it (any tool and by hand)

3. Will result in all items getting out of the box.