I deleted a folder from the content browser thinking I wasn’t going to need it. It was the SciFi Props Pack from the marketplace. I’d like to use it but when I click “add to project” all I get in the content browser is an empty folder.
Check if the empty folder also exists on your harddrive. If so, delete it and try to add the content again.
Fixed it. I had to close Unreal Engine 4, and close the launcher. Then reopen them, and when I clicked on add to project, it downloaded the missing files (I think). They are now listed in the content browser.