Ghost design file

Hi there!
I am writing to you about a problem of ownership I am experiencing for the first time.

When I joined my company, I switch from the professional plan to migrate files that were still in the free version.

However, the previous design file of an employee (who has since left the company) remains: it only appears in my recent files, I cannot move or delete it even though I am the owner.

The same problem applies to the previous owner of the design file, who cannot do anything with it. That’s why I call it a ghost design file: it’s in the team’s recent documents of everyone, all people can read or access it, and although I’m the owner of the file, I don’t know where it’s stored or how to delete it.

In order to keep the sharing links active and valid, I want to avoid duplicating this file in my drafts and then having to move it.
Hence my question: how do I know where this file is stored? How can I move it to a team under professional plan?
Thanks for your help :v: