The bug

When auto-jump is enabled, the game seems to check the incorrect block to decide when the player should jump. It is rather difficult to find out which block the game actually checks.

Some example scenarios include:

• Auto-jump triggers if you're walking towards a pillar of two or more blocks and there's a block south or east of that pillar on ground level.
• Auto-jump does not trigger if you're walking towards a block on ground level with a pillar of two or more blocks south or east of it.

Videos

Watch this video to see the bug in action.

In this video, you can see that the behaviour doesn't seem to follow any obvious pattern.

Original description

I was on my world and I had auto jump on. I walked into a slab that had a leaf block behind it and I started jumping. I tried this on other sides and it still made me jump. I tried this with another slab pole with no blocks behind it and I didn't jump. I also tried with regular blocks and I didn't jump.