Honestly I still don't get it. Just to make sure we're on the same page. I have a project/file in Fusion360 I want to share with someone. I generate the link using the dedicated menu. When someone clicks the link it tells him the file is empty.
Now your solution to this is to re-upload the project in a new file using the "Upload"-button and then share this re-uploaded file instead? How? Why? That seems to be designed incredibly stupid.
EDIT: I sort of get it now. The problem is that the shared file contains sub-files. That happens when you insert another file into your existing one. This creates a component which refers to the inserted file. This seems to turn the file to a folder, which contains both the original and the inserted files. For whatever reason file sharing isn't smart enough to read such a folder properly and instead tells you it's empty. To fix this you can right click the inserted component and select "Break Binding" (or so) to make the insert stop referring the original and return the folder back to a normal file.