1.9+ Elytras are not working, and if you jump and try to fly, they will not work, atleast on singleplayer worlds.

Put the summary of the bug you're having here

What I expected to happen was...:
I was just waiting to try the Elytras in 1.9. I thought they would work.

What actually happened was...:
I dropped from a height and tried to fly, but it didnt work.

Steps to Reproduce:
1. Get Elytras and try to fly from anywhere.