Some storage apps like OneDrive or Dropbox have a "Files on demand" setting, which only downloads files to the local system when they are accessed. In previous versions, FileSeek would download these files if they were in the directory it searched, but this setting will leave them unless they are opened.

That's correct, but it only applies to Dropbox or OneDrive files that are marked as "online-only." E.g. the file stub is in the folder, but it's not actually downloaded.