The developer confirmed this is the expected behavior.
After clicking the delete button in the archive set, run the purge deleted archive set job and the archive set contents will get deleted on the back-end. However, from the front GUI, the user will still see the archive set info with the status of deleted.
Maybe we can enhance this where the archive set will show 0 objects from the GUI or if the customer has additional comments. We can definitely submit it as an Enhancement Request for the future release.
In the meantime, you can query for SELECT * FROM DELETED_ARCHIVES_LOG if you are not sure anything happens while running the purge deleted archive set job.
Please note that the contents of the DELETED_ARCHIVES_LOG table only store temporary data. For example, if I deleted the archive #9 CHG-10, ran the job and then later deleted archive set 2 CHG-11, ran the job then the last info that stored in the DELETED_ARCHIVES_LOG would be CHG-11 archive set 1.