1. Please describe as detailed as possible what you did and which problem that leads to.
I'm trying to rebuild my maps to use proper undergrounds. However I cannot replace splines, tracks...etc to sublevels. I set them in the properties to be on -1, -2 level, rebuilt the terrain, but still all my levels are empty.
PLEASE DON'T TELL ME that the only way to place such thing is PLACE THEM AGAIN on the -2 level...