After my iTunes updated to 12.1.2.27 I lost the ability to sync with Outlook 2013 (Office365) on my Win pc running 8.1 (64bit) and I've read and tried everything here except removal and reinstall of all apple software. I too do not have the "ItunesOutlookAddin" showing up in Outlook. My SOLUTION, which is working so far, was to go to iTunes >Help>Run Diagnostics, plug the iPhone into the USB port and run the diagnostics, even though my iPhone when connected was able to be backed up, allowed access to the phones internal storage, etc. The diagnostics showed that "apple mobile device was not running". I then went to Programs & Features on the PC, selected Apple Mobile Device, selected repair. Restarted the pc and now my Outlook Calendar with all sub calendars appear in iTunes for selection and sync. A run of diagnostics again showed that the Apple Mobile Device was running but not the iTunes helper was not running.. go figure. But my sync works. Perhaps in the iTunes update that file was damaged.
Can anyone tell me how to get the iTunes helper working? and also the Outlook ChangeNotifierConnect addin is running but not enabled in Outlook for some reason. .