By default, most automations will skip records with existing data in the output fields defined in the automation's settings. However, it is possible to overwrite output field values with automations. You can enable this option by going to:
Your automation's configuration page
Processing Behavior section
Select Overwrite in Existing Data Handling
A confirmation will now be shown. Keep in mind that this automation will process every record during each run when this option is set to Overwrite.