I have a very strange problem. When I create a new project and choose the fiction ebook template, Scrivener creates the project but rather than a blank new place to start, it populates it with data from another project in another folder.
I am not aware of a “fiction ebook” template in our software. Was this something you created yourself, or perhaps downloaded from the Web? If you made it, might some old material be left in the template on accident? You can save a finished novel as a template and Scrivener will dutifully reproduce the entire novel whenever you use the template. That’s just how they work, they are “frozen” projects, everything that goes into a live project is going to get saved, all the way down to index card content and text.
Otherwise there isn’t a mechanism that would allow one project to pull data out of another project entirely, so I think the problem is more of one that looks like that is what is happening.