Hi Real Sways. Unfortunately, I think that map editor is no longer functional. I know what I'm saying, because all of my other mods (with varying requirements) work flawlessly. Map Editor is indeed the only mod that I have constant problems with.
I believe it is not your fault. Unless Map Editor gets some serious revamp, I don't think it will be functional. Strangely, I can still use stuff that require Map Editor. In my case however, I cannot either load or save any objects from any files at all.
I suggest you consider Menyoo as a map building tool. I assume it might even be better than Map Editor for some applications.
EDIT: I had a bit of a "revelation" and made a test. I was wrong - Map Editor does work.
The reason I believed it does not was that I could not open any of the "Community Races" with it. It might be a problem with "Community Races" coding, but not the Editor itself.
So, I suggest you thoroughly check the Map Editor requirements with special regard to the Microsoft .NET Framework as this is what most people forget to install.
Also, make sure you have a Native UI in your "scripts" folder. If you do, but have no luck running the Editor, you may need to use a different version of the UI (the one in the Map Editor download).