[ARCHIVED] Terrain paint disappears/changes after leaving lot

i just had this.

Demolished Slipshod Mesquite in Oasis Valley, deleted the lot's original terrain paint.  Did several hours work building a house & using terrain tools & terrain paint. Went back to neighbourhood view, loaded CAS to make a sim; when the sim was made & moved into the house, the terrain paint was missing. All of the terrain paint i'd done had completely vanished, only the slight colour variations from raising some sections of ground had remained.

(All packs, no cc/mods)