In the first image you showed me a directory. That has nothing to do with custom maps. That's your default maps folder and should be untouched. Regular custom maps will never show up there.
Custom maps belong in documents. Go the explorer path and paste in the path I just gave you and screenshot that.
%userprofile%/Documents/My Games/Halo 2/Maps
Edit: Btw you deleted default maps from the game like the campaign. You're supposed to have 41 map files in the Halo 2 install folder.