After being away for far too long, I've made my way back to the EM4 world.
Perusing the forums, I saw this, and after reading, I've discovered that I have the identical issue with my Editor for EM4 Deluxe from Steam. Identical load up. I get an error message when double-clicking the desktop shortcut though...
http://www.emergency-planet.com/uploads/monthly_2020_06/image.png.d6ad8ae353062c1e31dadefe332d9147.png
@Itch; I tried adding "-1" instead of "-editor" at the end, and it still loaded the missing map with the editor floor texture.
If there's anything you guys would like to try, I'm willing to be the lab rat..