My map is missing edges
Unfortunately, the map system cannot handle non-square maps. If it's non-square, the sides will be chopped so it's made square. I've tried several ways to fix it, but so far no luck. Hopefully one day there will be a good way of handling it, but we're not there yet.
The best solution is to open your map in Photoshop or another image editor and add padding on the sides to make it square.