Quote: "Come to think of it, I've had similar results lightmapping in ue4 with those same models. The engine gave an error that the models had overlapping uv maps. I have no idea what that means!"

Quote: "There are a couple of things you can verify here to make sure things are working correctly.

In the Mesh Viewer in UE4 make sure that you're got the lightmap coordinate set to 1 instead of 0. This will be located in the details panel to the right.

If you've got different UVs for your two UVs make sure to use the tool bar and verify that the UVs are different for UV 0 and 1.

The other thing to check is in Max add a UVW Unwrap > Open the UV Editor > Change to UV Channel 2 > Change to Faces select mode > Go to "Select" in the Toolbar > Select Overlapped Faces.

This will select any faces that are overlapped.

By looking at these two things we should be able to narrow down if there is an issue in Max or if we need to look at things in UE4 more."

Quote: "I wonder if this is what causes the odd shadowing in GG?"