NULL value for oldest and youngest items

Hello All,

I am trying to calculate how much storage we would be able to repurpose if we convinced our legal department to let us purge items older than 5 years.

 I ran this query in our SQL environment but the results are not complete (screenshot attached).

USE EnterpriseVaultDirectory
SELECT ArchiveName, OldestItemDateUTC, YoungestItemDateUTC, HighestItemSequenceNumber, IndexedItems
FROM EnterpriseVaultDirectory.dbo.IndexView
ORDER BY OldestItemDateUTC

The majority of the archives return NULL for the oldest and youngest items. Is there a way to synchronize the tables?

Thanks in advance!