Ender Chests don't pass items to Hopper!

I would think that Ender Chests would work as a chest and pass their items to hoppers

But when I tried it out, the items did not leave the Ender Chest

Steps to Reproduce:
1. Just put a Hopper above a normal chest and a Ender Chest above that,
Then if you fill the Ender Chest, it won't pass the items