Some of our end users has reported that the tracking response for Conference Rooms (Resource mailboxes with "AutoAccept" enabled) is changed to 'None' after updating meeting date/time.

Consider the following scenario:

User creates a meeting request and invites a resource mailbox.
The resource mailbox automatically accept the meeting and send an "Accepted"-message back to the Organizer.
If the Organizer at this point view the Tracking-tab of the meeting, the tracking response is "Accepted", as expected.

The Organizer updates the date/time of the meeting.
The resource mailbox send an "Accepted"-message with the updated time back to the Organizer.
If the Organizer now view the Tracking-tab, the tracking response has changed to 'None'.
If you look in the "Scheduling Assistant", you can still see that the Resource mailbox has allocated time for the meeting though.

We tried the troubleshooting mentioned in MS Support Article: 2215547.
 -Invited a Resource Mailbox to a Meeting and instantly closed Outlook after updating the meeting with a new time.
 -Located the Accepted-message sent by the Resource Mailbox via MFCMAPI, but couldn't find the PR_PROCESSED property at all.
 -After launching the Outlook-client, the PR_PROCESSED is present, but the tracking response is changed to 'None'.


 - We can't re-produce the problem in Outlook Web Access.
 - We are only able to re-produce the problem with "Cached Exchange Mode" enabled.
 - We are able to re-create the problem in safe mode, which should rule out any faulty add-ins.
 - Since the PR_PROCESSED property wasn't present while the Outlook-client was closed, the meeting response shouldn't have been processed by another device.
 - We can re-produce the issue on several different clients and several different Resource Mailboxes.
 - Office 365 environment, Outlook 14.0.6131.500 (32-bit), Windows 7 Enterprise (SP1 - 64bit)

Any suggestions for continued troubleshooting would be much appreciated.