Summary of Bug:

What I expected to happen was for me to enter the empty space and for me to place blocks within it.

What actually happened was it wouldn't let me enter the empty space at all. If I attempted to enter it, it would prevent me from properly moving.

I'm not sure how this bug was triggered. I logged into my Single Player world and it appeared out of nowhere. I know no one was griefing my world because I'm the only one in my household who knows how to play the game.