Can't move meetings between calendars in Outlook for Mac
Original KB number: 2803557
Symptoms
In Microsoft Outlook for Mac, you can't move a meeting by dragging it from one calendar to another. Also, there is no Move or Copy option to move meetings from one calendar to another.
Cause
If you move a meeting from one calendar to another, the action might trigger discrepancies between your instance of the meeting and the information that the meeting organizer or other attendees have. In such a scenario, you might miss important updates sent by the meeting organizer. Hence this functionality isn't supported in Outlook for Mac.
Workaround
To work around this issue, forward the meeting to the account associated with the calendar to which you want to move the meeting.
More information
Although you can't move meetings between calendars, you can move appointments between calendars. This is because a meeting is a calendar item that has attendees, while an appointment is a calendar item that doesn't have any attendees and is only on your calendar.