So before I say anything, I’ll say this: I know in creative when you hold jump with an elytra equipped you glide up. I know this is an intended feature, which is why I’m specifying this is not the problem I’m reporting. The issue I’m reporting relates to this though. When you are flying in creative with elytra and double tap jump to exit elytra fly mode to go into creative fly mode, it keeps you in elytra fly mode. It slows you down but still moves you forward, keeps your physical appearance is fly mode, makes you unable to go backward, and makes up & down arrows move you faster. This is a kinda confusing description so…

Steps to replicate: 

1. open/create a world on pocket edition
2. go into creative fly and go at least 50 blocks above ground 
3. equip an elytra 
4. enter elytra fly mode 
5. after gliding around in elytra fly mode, double tap jump to go into creative fly mode
6. try to go forward, backward, side to side, and up & down
7. Fly to the ground and touchdown 
8. go into creative fly and fly up 
9. repeat step 6 

expected results: you will be able to exit elytra fly midair and enter creative fly, standing vertically upright and be able to move in any direction

observed results: you stay in the horizontal elytra fly position, you instantly slow down and continue to move forward, you cannot move any directions but forward and up & down, moving up & down is faster than creative up & down speeds