Open your .esp in FO4Edit, find the corresponding entries under "Armor Addon" and "Armor". Under BOD2, edit the "First Person Flags" to uncheck 34 and 35.
Possible reasons: 1. Texture resolution isn't a power of 2 2. Issue described here 3. BSSubIndexTriShape block details were not set properly as described here I think 3 is the most likely.
Meshes need to be in BSSubIndexTriShape format rather than BSTriShape. I don't know if straight converting within NifSkope would work though, it should be BSSubIndexTrishape when exported out of Bodyslide.