Hi Domid,
Your FBX has materials already assigned at sop level, so when you apply /shop/octane_diffuse1 to your female body, the shader isn't used as he's using the ones defined by your fbx node.
If I where you I put that body in another geometry container using an object merge, this way, if you have to reload/swap your fbx, you keep it non destructive.
Then you can remove the material assignments with an attribute delete (delete shop_materialpath prim attribute). Once you do that, your geometry level shader will be used.