Elytras don't work when going under blocks at all (instead of only performing the gap glitch)

When using an elytra under blocks that have a gap to an air block, the player is pushed regardless of when the gap glitch is being performed or not (by gap glitch I mean the glitch that lets players walk in 1 block gaps while using the elytra). I don't know if this has to do with MC-90099, but it's an issue no matter the fact.
Here is an example: https://www.dropbox.com/s/w721yl0kv9ahrr5/Gap%20Glitch%20Fix.mp4?dl=0

Fix 1: The player is only pushed outside when in walking mode, not flying mode

Fix 2: MC-90099 is re-addressed in the snapshot (hit boxes under blocks)