Intersection Asset Won't Place in Game!

[gabrielcrandall 0]

I have had the game ever since it came out. I just barely finished making an intersection in the asset creator and it took me two hours. I tried to place it in the most flat map, on the most flat area and it tells me slope too steep. Then I moved it over every pixel on that map and it tells me that I can not place the thing. I try it with the already built in game ones, and they work perfectly fine. Can anyone explain to me why this is happening with the intersection I made. If it helps out with the search, I have every DLC possible in the game. I am extremely sad because I know for a fact that it did not do this in the older versions.