Exchange mailbox of user from other domain not showing under recoverable item

I run in to a rather strange issue with restoring mailboxes for a customer DPM implementation.
They have an Exchange 2007 SP1 CCR cluster on Windows 2008 SP2 in domain A.

The Exchange cluster is protected with a DPM SP1 server on Windows 2008 SP2 also in domain A. The Exchange server hosts mailboxes from users in many different domains but in the same forest.
The creation of recovery points works without errors and the log files are cleared as expected.
The issue is with recovering a mailbox. When selecting the recovery tab in the DPM administrative console, and select the Exchange cluster, then the storage group and then expand the mailbox store. Here under recoverable item I would expect to see all mailboxes in this mailbox store but instant we see only some of the mailboxes. Infect only the mailboxes of users located in the same domain as the Exchange server (domain A).Recovering the mailboxes is not a problem. When doing a recovery of the mailbox store to the recovery storage group all mailboxes in that mailbox store can be recovered this includes the mailboxes of users in other domains.


UPDATE: There is a hotfix rollup package for System Center Data Protection available that fixes this and 13 other issues. The hotfix number KB 968579 (thanks to Nagesh [MSFT] for pointing me in the right direction).
This also brings me to another important link: Recommended hotfixes for Microsoft Data Protection Manager 2007 systems.