Inventory for S3 Glacier vault shows last update years ago...

I am trying to delete a large number of archives from an S3 Glacier vault that I decommissioned last April. I have been able to get details, initiate an inventory retrieval job, and use a script to try and programmatically delete the archives in the vault as there are over 900,000 archives between the two vaults.

I suspect since the last inventory date showing in the console is Feb 2016 (you did not read that incorrectly) that subsequent tasks may not work as the inventory doesn't match what is actually there. I am not sure if this was due to how they were created (Synology NAS backup application) but I thought they refreshed the inventory every 24 hours at a minimum.

Any thoughts on how to proceed? Don't have a support agreement, so looking for community suggestions. Thanks!