Changes only HCM extract still pulls the full file even when there are no changes

Summary:

We currently have a full file extract(Full Profile) which sends the Check payment details to the bank and now the requirement is to change it as changes only file . We exported the Full file extract and import it again with new name as changes only option enabled . Also , we have choosed the Threading database item as Extract Employee person ID and marked few attributes(Person number, Check Number) as Key attribute in the records.

We submitted the extract with all attributes to get the full file in the first run and subsequent runs submitted as changed attributes. Though there is no changes to the data , we get file is getting extracted instead of changes only file . The expectation is to get only the unique check payments record in the extract.