We are currently utilizing Office 365. Microsoft has been unable to resolve this issue, so perhaps someone on here has seen this and knows a solution. As mentioned, we are on Office 365 using a Federated Server. Calendar Sharing within the Outlook client ceases to work if the Free/Busy with Details permission level is selected, however, OWA allows access to the calendar. Changing the permission level to any other level, such as Reviewer, will fix the issue, and this has been suggested by MS as a workaround. Unfortunately, this is not acceptable to some of our executive staff.
This is easily recreated within our environment on any PC, sharing anyone's calendar with any user. A common MS suggestion is to use powershell to set the permissions, and we have tried that, as well as recreating outlook profiles several times. In all, it appears to be relative to only this permission level.
Any ideas would be appreciative.