Elytra aren't functioning.

Put the summary of the bug you're having here

What I expected to happen was...:
My brother and I tried jumping off a cliff with Elytra on my LAN world, just to quickly get down there.
What actually happened was...:
The fact that we had Elytra was totally ignored and we just fell like we weren't wearing any.
Steps to Reproduce:
1.Jump off a cliff
2.Fall