ContentIndexRetryQueueSize value for a passive node never drops to zero in Exchange Server 2013 Cumulative Update 6

In a Microsoft Exchange Server 2013 Cumulative Update 6 environment, you receive a notification from Microsoft System Center Operations Manager (SCOM) or other monitoring tools stating that the ContentIndexRetryQueueSize value for a passive node of a database availability group (DAG) is very high.

Note To verify that you are experiencing this issue, you can implement the following steps:

1. From one of the Exchange Server 2013 servers in your environment, open the Exchange Management Shell (EMS).
2. Run the following command, replace <server> with a backed Exchange Server 2013 server in your environment:
   Get-MailboxDatabase -server <server> | sort -Property name | Get-MailboxDatabaseCopyStatus | select name,status,content*

If you are experiencing this issue, the ContentIndexRetryQueueSize value for the passive databases will be between 100 and 300.