Data showing unaccounted when viewing a period greater than 1 hour

Data showing unaccounted when viewing a period greater than 1 hour

We have build 9900 Essentials version of NetFlow Analyzer installed and average between 5k-9k flows per second.  I have Count of Top N Records to Store set at 100.

In an Interface view, if I set the period to <= 1 hour I can see the Top N detail, but if I set it to anything > 1 hour then it shows everything as Unaccounted.  So long as the period I specify is 1 hour or less I can go back 5 days and still see all the Top N detail.

Does anyone know what is stopping me from viewing the Top N detail for periods longer than 1 hour?  If that is possible, how far back should I be able to view the Top N detail? 

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