I built a custom dungeon, and before exporting it, I decided to move it up one block. Instead of that happening, a third of the structure was erased, and a ghost selection is now permanently rendered around the build. A generic error message also popped up in the chat. I tried selecting a different area, and that entire cube of selected area is still there.

For reference, the exact command I typed was "/#move -y 1"

Definitely not touching that command again anytime soon. xD