please read my question and comments carefully before replying.
We just upgraded to Outlook 2013 x64bit and exchange 2010. there is only one exchange server with all updates and fixes installed, and Outlook is up-to-date as well.
User A sends a meeting request with tentative appointment to user B
User B accepts the appointment and it shows on his calendar as tentative
User A changes the appointment from tentative to out of the office or busy and sends update to user B
User B receives the update and click on No Response Required
User B's calendar does NOT change from tentative to out of the office or busy.......
we tried OWA as well as tried this in cached mode and online mode and made no difference.
you can see that communiation is real time between the two clients and exchange because as a test, I changed the words and client machine immediately updated but the free/busy/out of the office status never changes unless you change the time of the appointment.
Please let me know
David