If a player is standing on the edge of a honey block he can jump normal, this also happends with auto-jump on. I think this has to do with the hitbox of the honey block because it is different then all the other blocks.

-Photo 1

you cannot jump when you are standing on the inner block (The Red part)

you can jump normal when you are standing on the outer layer (The Blue part)

-Photo 2

An example for what i meant with auto-jump.

If you are staning on a honey block auto-jump does not jump when there is a block in front of  you (~1 ~1 ~0). But if the block is 1 block further away (~2 ~1 ~0) and you walk towards that block auto-jump will jump for you.