I have run into an issue with the latest iPhone software (iOS 6 and 6.0.1) whereby when I recieve calendar invitations from outside of my company I cannot accept the invite. I have spent 3hrs working with Apple to resolve the issue and they have directed me back to Microsoft, who they said would contact them if the bug is on the Apple side. I have confirmed this issue only repros on iOS6.x and not on iOS5.
Issue:
When someone outside of my company sends me a calendar invitation to my Office 365 hosted exchange account I can view the invitation but the Accept, Decline, Maybe buttons are missing. When I view the invite within the calendar the buttons are shown but pressing them does nothing. It appears that the context of who sent the message is being lost since it shows as from "somebody". (see screenshot https://skydrive.live.com/?cid=76e4f0dbd8631804&id=76E4F0DBD8631804%21188&action=Share)
Troubleshooting so far:
As mentioned above I worked with Apple both at a store and on the phone to troubleshoot. I confirmed this issue repros on iOS6.x but not on iOS5. I also confirmed that my coworks with iOS6 have the same issue as does my wife who works for a different organization that is also on Office 365 hosted exchange. I wiped my phone completely and just added the Office 365 email account and still saw the same issue.