did you deleted the map.rwm in world/maps/campaign/base?
moreover, try to delete the txt.strings from data/text, the ones dated 2018 (last edited ones)... I didn't do that for the CD version, just the map.rwm, but I guess for Steam is good to do... they are regenerated after you start the game... they always have to be 72 elements in that folder.
and be sure you extracted in the correct directory mods of your MII....
Let us know, so that I also correct the steamer installation when you resolve.
https://www.youtube.com/watch?v=pIa7OUMNVPI
(it's almost over this season)