Many users have reported that the Outlook 2013 calendar permissions not working. There are some standard instructions available for you to share your calendar permissions in Outlook. You also have the facility to add, remove, or review the permissions that you have delegated in Outlook 2013.
Let us first look into those standard instructions to share calendar permissions in Outlook 2013:
However, in some situations, the above standard instructions fail to work. For instance, some users attempt to set permissions on a shared calendar. These users have got the correct permissions on their calendars in Exchange; still, they complain that the Calendar Permissions button (or option) in Outlook 2013 is grayed out when they try to set permissions.
The Calendar Permissions button in Outlook will function only for the primary/personal calendar. But, when a shared or resource calendar is chosen, this button will be grayed out.
Another reason for the calendar permissions issue in Outlook 2013 could be the following:
The Calendar Permissions button might look grayed out because the IT department in your organization could have blocked the permissions for calendar sharing as a part of security precautions.