Lighting "always" needs to be rebuilt

I had this issue as well, in my case it was caused by using the “light as if static option” on movable meshes. As soon as one of these meshes touched the radius of a light that it did not touch in its initial position the “lighting needs to be rebuild” message would pop up.

This also happened when the mesh was moved in a packaged game. Maybe this is also happening in your scene?