Turned out to be something wrong in the cache located somewhere in AppData\Local\Unreal Engine.
I removed the folder and was immediately able to run and load the editor again. I should add, the issue started to affect the Epic Launcher as well.
The other day I opened a project, and noticed it got about 50% done loading, and crashed. This now happens with all projects using the launcher version of the engine. I can switch the engine version for projects to a source-built copy I also have installed, and the projects will then load. I have re-installed the engine in the launcher, and it still happens. I can’t even launch the editor without a project to make a new one without it crashing.
EDIT: Removed files.