When standing in the 1/8 block between a chest and any other block, you cannot autojump.

Steps to reproduce

1. Open a world.
2. Place a chest and any solid block right next to a chest.
3. Make sure autojump is on.
4. Stand in the same block as the chest and attempt to autojump.

Expected results

You jump onto the block.

Observed results

You cannot jump onto the block

Postscript

I have not done much testing on this. I only noticed this in my world after playing with my friends, so I would appreciate it if someone else helped me with this.