CANNOT USE ELYTRA

Put the summary of the bug you're having here

What I expected to happen was...:
I expected to be able to glide/fly with one of the elytra classes

What actually happened was...:
In the Cisco Adventure mod pack, one of the classes allows the player to fly/glide. That doesn't happen. I can use the fly ability but cannot glide and when I fly it gives me a "Flying is not Enabled" error

Steps to Reproduce:
1. Sprint off a cliff
2. Press "G" to use flying ability,
3. Fall and hold space bar

 

Using the ability works most of the time but after 3-4 uses consecutively the game will crash. The glide ability is a passive. I t should work just like a regular Elytra but instead of gliding, I just fall