Expectation:
I think player should be able to walk out because player is not that tall

Actually happened:
I am trapped, I can't move out of that spot

Steps to Reproduce:
1. choose a flat place
2. place a 3x3 panel of any block just above your head, so player can go underneath
3. stand right under the center of the panel, remove the block above your head, and then remove the block you are standing on.
4. place a block with height less than 1 unit (i.e. End Portal, Chest) under your feet, make sure you are standing on it
5. Try to walk out that place or jump! Either won't work