Folders Not Visible On ActiveSync Device
Missing folders on an iPhone, Android, Windows Phone, BlackBerry, or any mobile device typically occurs with folders that were imported from another service (IMAP, etc.) or an older version of Outlook. The missing folders and their content should still be visible in the mailbox on the server.
Re-create the folder in the Exchange mailbox using Outlook or Outlook Web App (OWA). Two nested folders cannot have the same name within same parent folder hierarchy. To work around this add "2" after the new folder name.
1. Move data from the old folder to the new folder.
2. Delete the old folder and remove "2" from the new folder.
3. The new folders should now be visible, and synchronize any content in the sync duration criteria with the mobile device.