So that what I meant by strange. Btw I have this error in the console too I think it can be (maybe) related :
"There are 11 objects in the Scene with overlapping UV’s. Please see the details list below or use the ‘UV Overlap’ visualisation mode in the Scene View or Lightmaps in Lighting Settings for more information.
I’ve seen the manual but I didn’t really understand because nothing actually showing with the UV Overlap (except the wireframes but I don’t think is the problem source) look:
My first thought is to check your vertex normals on the mesh.
I’m assuming there’s a mesh edge where your light seam is, if you have custom split vertex normals then it will direct the light on the mesh to bounce in a different direction.
Sometimes the issue can be negatively scaled vertex data. Even if the normals are facing the correct way, there can be an issue in the underlying mesh data where the normals are still flipped (common when combining negatively scaled meshes in 3dsmax into a single mesh).
The only way to fix it for certain is to take the mesh into blender or similar and reset the normals.
I’m going through the exact same problem. I have downloaded a sample scene from the asset store and when I tried to bake the lighting for the scene I’m having errors just like you. I thought maybe there is something wrong with the sample package so, I created a fresh scene(it contains a plane, a cube, a cylinder) and tried to bake the light and still received the uv overlap error. And in my case this happens when I increase the Lightmap resolution to something like 10 from 2.
I think I have found something that is going to work.
After reading the answer of ‘rasmusn’ from unity technology I did what he posted as a gif and increased the Lighmap resolution. Well scroll down in that thread read his answer(maybe his post at number 13) and try to understand those things.
