Firework flight doesnt work in snapshots in random worlds

So, whenever I load up a world in a snapshot, it seems that firework flight doesnt work. as in, I fire a firework off into the sky instead of getting boosted.

To recreate:
1. Load MC in any snapshot
2.Load a new world. (Occurs most in superflat)
3.put on elytra
4.get fireworks.
5. Watch as the fireworks dont boost you...
ALSO Sometimes they WILL work in worlds that previously didnt work. I cant find a correlation... Help