Calendar Problem: Private Items Not Showing (Outlook 2016 for Mac)
By marking a calendar item (appointment, meeting, or event) as Private, you hide the details of the item from people who have permission to view your calendar. Users of Outlook for Mac 2016 are not seeing what they're supposed to see.
This article applies to: Outlook 2016 for Mac
You can grant others permission to see your calendar. You choose the level of detail (when you're free or busy, the subject of the event, or the details of the event). You also have the option of marking a calendar item as Private; this removes all privileges except seeing that you are busy for the duration of the calendar item.
Outlook 2016 for Mac has a known issue with the Private flag. When someone uses Outlook 2016 for Mac to view another person's calendar, items marked Private do not appear at all. Apple is aware of this problem.
The current workaround is to view other calendars from Outlook on the Web.