Could you explain in detail what the terrain masks are and what they are supposed to so?
I assumed if they are dark, nothing can be populated on anything.
I turned off what I assume is water (right), but I can drop buildings in the water.
I now find the wavy line is not water, but the hump to the left is water.
I turned off all three and can still drop houses into the scene.
Everything off, the terrain cannot receive anything. See P.S.
Everything on. nothing is sacred.
P.S. The terrain mask works for everything except the objects in the house group.
water does not let me drop things into the water. I must also select one of the other icons.,