I too suffer from this problem. I can find no reason for it. It frustrates me becuase I built an entire mod in the side of a mountain only to realise when testing I was inside a Snow Cliff and Snow mountain. I also ran into another issue, I made a seperate mod in the Northwest region of Tamriel. I landscaped an area, tested it and used it with HCAD and Shacks. It was fine till I did a reinstall of my system. The saved area allowed me to build but i could no longer access the route in game, it just kept telling me I can't go there. I checked meshes etc, still nothing. This only seems to have developed recently, I am not sure if Steam did something or if maybe it has something to do with a mod. Though I can't imagine which mod or mods may be causing both issues. I will continue checking, perhaps a senior well experienced modder can point us in the right direction.
