I have a very strange issue that I have been dealing with for a few months now.  In January 2015 we migrated from Exchange 2007 to 2013.  Ever since the upgrade my users have been calling at random explaining that the Public Calendars they have added as favorites have disappeared.  This issue thus far has been random without any pattern we can find.

We have tried every Google suggestion we could with find no solution being found.  ResetNavPane, Updates etc.

The temporary fix for the issue we have been practicing: we close Outlook, remove the users Outlook profile and then have them open Outlook.  This process every time brings the Public Calendars they have made as favorites back.  However this process is both annoying for the users and IT.

A little background, all of our users are setup with roaming profiles but we are only roaming their AppData.  The remainder of the folders are being redirected to a DFS share (Kept in sync between two sites) for folder redirection.

Also, 99% of our users are set to use Online mode due to the challenge of roaming often, sometimes up to 2-3 different desks a day.

• Edited by SBONate Friday, July 10, 2015 12:56 PM

See a similiar issue related to Exchange 2010 version:

https://support.microsoft.com/en-us/kb/2599434

This issue occurs because the Public Folder Calendar folder in the Favorite list cannot be recognized correctly when the OWA Calendar module is loaded. Therefore, the folder is incorrectly added to the InvalidNodeList list, and then the folder is removed.

Not sure if this applies to Exchange 2013 version.