UMAP won't load in editor

I have a UMAP in the file explorer, but it won’t show up in the Content Browser in Unreal Engine. For some background, my current project got deleted… the project file but I had all the content, so I created a new project and all of my content (Blueprints, meshes, etc.) All came over fine (so thankful for that and not having to restart!), except for the maps. My mainmenu map works fine… but everything else doesn’t, even things as simple as a blank travel map. Any ideas?

Here you can see “Arena” in the file explorer:

But it won’t show up in content browser, and when I try to drag in, I get this error:

Both projects were on the same version, and both have the same plugins, etc.