We've seen some issues where IMAP folders in Microsoft Outlook 2011 for Mac go missing. We're not sure why they go missing, but we do know the fix:
- In Outlook, select Tools > IMAP Folders...
- Using the resulting Folder Browser window, navigate through all your folders looking for any that are NOT bold (the missing folders).
- Highlight any missing folders and choose to Subscribe (click the Plus button in the upper-left)
Close the window and your missing folders should reappear!