Thanks .
To elaborate… In Blender, I selected the mesh. Hit A on the keyboard and searched for Lightmap Pack. Selected it from the search results. When it opened I kept the Lightmap Pack defaults and hit OK. I then re-exported the fbx and then reimported it into UE4. I actually deleted the existing mesh and all of the graphics for it and reimported, but probably not necessary to delete first. It worked for both meshes giving that error.
Thanks again.