Troubleshooting & messages · Moves and copies that didn't finish
What does "Something starts up with your Mac using these files" mean?
Short answer: A helper that starts with your Mac uses those files, and your external drive may not be ready that early — so Storage Studio leaves them on the internal disk.
Something that launches when your Mac starts — a helper, a login item, a background service — uses those files. At startup your external drive may not be connected or ready yet, so the helper would find nothing and could fail or start fresh. Storage Studio leaves these files on your Mac.
If you no longer use the app behind that helper, remove the app or its login item, and the files may become movable.