A handful of people are also reporting that after updating to Office 2011 14.1.3, their Outlook randomly stops updating the inbox, requiring a quit/relaunch to get the inbox to update again.
When this occurs, Outlook will report that new mail is being received, it just doesn’t show in the inbox. Another reported issue is mail remaining marked as unread (bold) even after read. These issues aren’t affecting everyone, and manually downloading/reapplying the 14.1.3 updater from Microsoft’s website had helped some. Also of note, this may be linked to not rebooting after applying the Microsoft update. Although it isn’t required, some have resolved these issues simply by rebooting their Mac.