I am making an game with Unreal Engine 4. In the editor of UE4 everthing works out fine but when i am exporting the Game to ship it, the Ground of my Maps disappears. Its the correct Map, there are my player, the House etc … but the Ground is missing. 
I already tried setting it as the default Map, now it is, but this didnt fix the Problem sadly.
Can you help me with this Issue? I am completly helpless. I’d would be so thankful