No dice. No matter how I export it out from Blender (face smoothing, tangents and different permutations) and import it into UE4 (mikkT always, importing or computing tangents/normals), the seam is just always there when I bake the lighting. You can see from the picture that when the mesh is duplicated, the seam is invisible (with the white default mat) and barely visible with some basic material on it (the checker texture hides the seam perfectly). I just don´t know what more I can do here. I even stripped the mesh down to its basic form and rearranged the UV space so that each island has plenty of space between each other and the main island has sufficient space from the edges. Nothing helps.
