Confirm the file still exists at the scanned path and close every application using it. Pause synchronization and keep its volume mounted.
Check whether the disk is writable, unlocked, and owned by the current user. A network share or read-only medium can prevent removal.
Grant access to the containing folder and approve only matching authorization. Do not weaken System Integrity Protection for a protected unknown item.
Run a new scan or re-add the current file. A stale selection can refer to an item already moved.
A failed operation should not be treated as successful; verify the file and all synchronized copies directly.