All questions regarding the GSC.

The files GroundTerrain.bin and UnderGroubd.bin are responsible for the terrain. It seems that one of them is corrupted, and the map editor breaks it during map packaging.

However, the maps open and work normally on my editor and in my game. I even reinstalled the game and then installed a completely different version, and they still work. For some reason, this problem only occurs on my friend's computer.