I've tried to take the heart stone harness from Ildari's robes and make it into a separate piece of apparel (using NIFSkope), but equipping what I've got does nothing. The menu reads it as equipped, but it doesn't show up on the character.
Armour form: http://oi62.tinypic.com/334riub.jpg
Armour AA 1: http://oi62.tinypic.com/2ik45eo.jpg
Armour AA 2: http://oi61.tinypic.com/t4wd5h.jpg
The Heartstone AA is simply a copy from Dragonborn.esm, using different equip slots. The .esp uses Dragonborn.esm as a master as well.
NIF file (harness): https://www.mediafire.com/?4cfw5oweztoi9mm
I've tried changing equip slots, I've tried removing the harness from the armour form in case of a mesh issue. Even so, both the meshes for the heart stone and the harness show up as a preview in the mesh selection dialogue box. I'm at a loss, although I may have missed something really silly. Can anyone help?