My Car falls through the terrain

[PamLiam]

I am new to Unity ang LGSVL. I build a map (Map-05) and in Unity the Preview is OK. after the building the Map and Importing to the LG website (the Map Preview) still is OK, but after running the simulation nothing is loading and all Map space is empty and when I click the play BTN the car falling Down to the infinity! Anybody can help? May map available in Site (Map-05)