I helped a customer with an issue where the .ics attachment sent from their travel agency that was supposed to have travel itinerary in the body of the .ics file was blank. As one could image this caused great grief for their folks that are on the move.
This particular customer is using Outlook 2010 in online mode with Exchange 2013 CU5. We found if a user was using cached mode the .ics attachment's body was displayed. I spoke with my colleague Michael Epping
about this and he hadn't heard of this issue, then 2 days later he lets me know that Exchange 2013 CU6 was released and this KB was publish (http://support.microsoft.com/kb/2975003).
After installing Exchange 2013 CU6 the issue is resolved. Thanks Michael!