Steps to reproduce

1. grab a shulker box
2. grab an elytra (put it on obviously)
3. mine 1 block down then place the shulker box in the hole facing up
4. go atop the shulker box (in its opening area)
5. open and close the shulker really fast once
6. while it's still in the opening animation press the jump button
7. if you did it correctly you should see a weird but brief moment while the player is in the flying animation

Expected Result
Player should simply jump on top of the shulker box whether opening or not

Observed Result
Briefly shows the gliding animation when shulker box is opening