Gameobject turned invisible because of fog

Im building a game to an android, and for some reason the "ground" object didn't render at all.

but after getting at the very end of the level, it finally render itself. I suspect it was because of the fog, because after i turned it off the object became visible again. im asking is there's anyway i can make the fog to ignore the "ground" object or atleast make it visible ?

thanks in advance P.S. another question. in the game view it's seem to be doing fine, but after i exported it to android the issue started, is there any reason for this ?