What are LOD's?
Levels of detail. It's a lower poly version of an object which loads when you get further away to reduce fps lag. A gun might be 2000 polys, and drop down to 100 at maximum distance with lods, because at such a distance you may have 100 guns on screen, which without lods would have to be 200000 polys on screen rather than 10000 with lods. But you get invisible torsos when say the body has 4 lods and the straps have 3, when the 3rd lod for the straps is showing, it doesn't have a torso lod to show at that level, so it just shows nothing.