Unable to view entire map in custom world

I don't know if anyone has experienced this or has any idea on how to fix it, but if anyone knows I'm sure I can find them here. I have never been much of a custom world builder, but I decided I wanted to try the Prosperity challenge and so began my journey to make a custom world. Unfortunately, I am still bad at it and decided instead to download a custom world from modthesims. The downside to both creating my own and downloading a custom world was that I could never completely zoom out to view the entire map. It wasn't as noticeable in the empty map of the custom world I was creating, but with the downloaded one it is to the point where I can't see a good portion of the premade lots. Is there a reason why I can't zoom out to view the entire map like I am able to in the premade neighborhoods? It seems odd that they would give us the capability to build our own worlds and not allow us to view the entire possible map.

Any help or guidance you guys could give me on this would be greatly appreciated!