UE 4.12.3 Corrupt?: Assets Gone, Lightmap and Static Mesh Settings "Hidden"

Earlier today I had imported a gang of meshes into my project. I saved my files, left UE4 open and had something I needed to attend to. Hours later, I came back and “woke up” my computer. When I loaded my project back up, all but one of my meshes remained. The level I was working on was gone, and when I attempted to load the backups I just kept getting failed messages.

So, I re-imported my meshes, only to notice the Lightmap/UV index settings for my static mesh was “hidden” (I had to type in the search box for it.) The same thing happened with World Settings—all of the lighting info was missing, and only discoverable through search. Also, my content browser wasn’t attached to any of the planes, but rather floating in the middle of the viewport as it’s own window; it’s almost as though UE4 “reset” itself. When I tried to save new content, initially, I got a failed to save: “mesh only partially loaded” or something rather. I checked all the logs and haven’t seen any issues.

Now, I’ve since deleted the project, but I’m noticing–upon starting a new one–the static mesh lighting settings are still missing and have to be searched for.

Sorry, I know this is a complicated issue (a lot of things going on) but I would appreciate any feedback. I’ve searched relentlessly for answers, but as there are several things going on, I haven’t found what I am looking for. I’ve been holding back on re-starting the project