VT Lightmaps render different results and no shadows

VT Lighmaps don't have the same results as the regular lightmap counterpart and don;t render shadows.

https://udn.unrealengine.com/questions/578318/lightmaps-different-after-switching-to-virtual-tex.html

1. Enable VT lIghtmaps
2. Add some geo and static lights to a scene
3. Bake lighting
4. You should see the light info baked but no shadows
5. This is also reported that the baked lights results differ from the equivalent bake without lightmaps as per the following UDN:

https://udn.unrealengine.com/questions/578318/lightmaps-different-after-switching-to-virtual-tex.html