I apologize for the fact that I ^probably duplicate the post on a bug, but I had to.
After all, you could not see my post on the bug about switching mode in the space of 2 blocks.

This error has been present since version 1.20 and persists until beta version 1.20.
Error: When a player (located in a place 2 blocks high) enters crawling mode, he will no longer be able to switch to flight mode. But in the same conditions (the player being in a place 2 blocks high), when the player is not in
sneak mode, he can easily switch to flight mode.
Previous post: MCPE-172411