This is a duplicate (and fix) for issues
#23649 and
#23813, which were both closed as being impossible or unreasonable to address. Luckily, because Bethesda meshes have every material as a separate part of the mesh, it's exceptionally easy to strip the afflicted meshes down to just the problem parts, create new objects using just those parts, and place them in the affected parts of the map. The attached file fixes the hole in the floor mentioned in 23813, a hole in the roof I can't find an issue for, the holes in the tops of walls mentioned in 23649, and several more walls that present the same issue when viewed at specific angles that are well within bounds. This fixes all of those while making no changes at all to the precombines that the original objects are part of.

Attached Files:
Vault75Hole.zip