I'm really really new to Blender and nifscope, and this may be an easy fix, but yeah, the mesh entirely disappears in 1st person (before I merged the objects, they used to disappear one by one, depending on the camera angle).

Also, in cs, when I try and place it in the world, it ends up appearing underneath the cells (this may have to do with the huge 'bounding box'), and in-game it floats mid-air. But actually, it might be the textures, as the mesh itself appears properly, without the textures applied I mean. But I'm at a point where I'm not sure what to look for exactly.

I'll leave the nif file here, maybe I'm missing something very obvious.