This is because there is a collider on the hole that someone forgot to remove, the renderer thinks that you are still looking at a wall and not a hole and that effects your draw distance / culling.
I have to agree, there comes a time where you have to accept your engine is outdated and needs tossed. Arguably, you could say the same thing about the source engine but I feel it gets to be exempt on account of being so well done. (
Source Engine is very well optimized and Valve hasn't made a graphics intense video game for ages with the exception of Dota 2 and CS:S. Valve won't make a new engine for the sake of modders.
Since the engine is pretty well optimized all they needed to do for those 2 games is make it 64 bit to support high memory usage. Hell, they HAD to make it high quality because of CS:S and TF2. Can't have a **** engine for multiplayer games and expect to get a lot of customers.
It's not remotely the same engine, the modifications from Gamebryo to Creation engine are so extensive it is functionally an entirely different beast. And fallout 4 uses an even more heavily modified version.
This is not some engine bug or anything, it's a misplaced texture issue the likes of which are present to some level in the majority of games, particularly open world games.
That said I did run into a building where you could exit onto a balcony but the door didn't open the other way and you just walked into a patch of dirt with walls and looked out on the world like that so... yeah that, got stuck in there.