I have encountered this bug before and I didn't report it because I figured someone must have already, but browsing the bug forums now, it seems I was wrong. I had a lower class worker starve to death because of this before, and it seems in this case something similar is happening.
Uhhhh.... Issue a flatten terrain order Optional: Issue an overlapping order, like Clear Terrain, that will put another overseer there (this seems to happen automatically). This could also happen to a military squad, the lower class worker mentioned before was a redcoat. Maybe also a naturalist or foreigner. Get lucky ??? Profit
