Oh ok. Im a max user. I didnt realise that smoothing groups was a max only feature. I would hate not to have them but I guess this is a whole new debate ;). Seems you have fixed your issue now but I searched on google for "maya smoothing groups" and found this.…
Note that you generally want to go the other direction... generate UV seams from hard edges. To reduce shading errors with tangent-space normal maps, it is best to split and separate the UVs where there are hard edges on the model. Hard edges are not needed for every UV edge though. I.e. there can be more UV edges than…