Hi Frankie, thanks: am I right in thinking that “smoothing groups” is simply how Max users and the like refer to what we in the Maya world would call hard/soft edges? If so, like I said, all edges are softened (and locked/unlocked, transferred, hardened and re-smoothed and re-smoothed to make sure, and then to make TRIPLE sure it’s not the mesh…) and sewn in both the texture UV’s and the lightmaps. It was exported with smoothing groups checked in the FBX exporter, and lights normally in other circumstances. Actually, it was pointed out to me that similar problems show up in the GI of even the starter content’s example assets, when you crank their lightmap resolution really high. Curious.