Disappearing LODs {SOLVED}

I'm trying to create some edits of the Vampire 'pearl' necklaces and I've saved the meshes and they show up just fine in LOD0; but whenever I try to load anything into LOD1 or above, they vanish. I've tried starting the package over from scratch. I've tried this on both Harmony and Wishes versions of S4S. I've tried just loading the LOD0 version which shows up in LOD0 into LOD1, but it, too, disappears. I'm sat here scratching my head.

The mesh itself seems fine.

I have now tried importing it over a base game mesh and it's still disappearing the LODs for the necklace slot.

Any ideas?