Stale/Not Collecting object not being purged/deleted

Hi,

We have many objects that are not being deleted from vROPS even after the "Object History" has been passed a long time ago.

For example as you can see in this picture:

We have many Datastores that are not collecting data (they have been deleted a few years ago), but still show up in vROPS database.

Here are our "Global Settings":

As you can see, they should have been deleted after 300 days but this didn't happen..

When trying to delete the object manually it works, but since there are thousands of these objects, we can't go and delete all of them manually.

We recently upgraded to vROPS 6.4 because VMware told us that this problem should be fixed by then (and it didn't..)

Does someone know what is the issue here? or what should I search for?

Thanks!