It's not a bug, it's an event. If you paid attention to the scene you'd realize that.
Regarding the Midnight Fence, he is meant to be inaccessible when you play as God Emperor. The intended meaning behind this is that he recognizes who/what you are an is confused by your presence at that point. He doesn't remember much, but he knows that it is not yet time for gods to walk the earth once more.
Oh and Datawungui, what scene you are talking about. sorry for me asking this. there are so many things to do in this game, I might have missed the mention about this. can you tell me in which scene does it tell us so?