I explored further, since I did this pretty quickly and found you can change the replicated terrains thickness, hotpoint and position, if needed so the terrain you are using is above the white replicated grid. This eliminates the render issues that I can see.The grid which is acting like a solid is now under the terrain. That way you don't have to insert another terrain. So it is really just a bad choice for the default settings.I did report it tho.

No need to think outside the box....
    Just make it invisible.