Symptoms
When you run the Get-ExchangeServerAccessLicenseUser cmdlet to return a list of unique users for the specified license name in a Microsoft Exchange Server 2013 environment, the result for the number of the Exchange Server 2013 Enterprise CALs license displays nothing.
Cause
This issue occurs because the Get-ManagedFolderMailboxPolicy cmdlet in the CalCalculation.ps1 script that is used by the Get-ExchangeServerAccessLicenseUser cmdlet is no longer supported in Exchange Server 2013.
Resolution
To fix this issue, install Cumulative Update 12 or a later cumulative update for Exchange Server 2013.
Status
Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.