May not be a bug rather something of my doing.

I'm creating military base everything is completed but the issue is entering it. I walk up to the door and enter after the load I'm in a giant grey place (Out of the map) I walk around I can hear my steps on what should be the floor. When I adjust my screen a certain way above me is the building I should be inside. When I walk straight for a distance I start fall and fall then the speakers make some fuzzy noise and I appear inside some building in the middle of D.C

What the hell do I do? It's really annoying; I have never had this issue before. I'm no experienced modder guy so I’m very aware this might be some issue I created.

I'm not sure if I recall correctly but I think there is some limit to the internal x,y,z coordinates - did you start building at an edge of these?