I created a report based on the Event History Subject Area and when I include fields from the Owned

If you remove the Owned by User fields, the row comes back. If you then add a fact (like # of Invitees or # of Events), no rows come back. Which is why you see no rows when you include both Event and Owned by User fields (two separate dimensions, it automatically includes the implicit fact which is based on Invitees). When there are no Invitees, no rows will come back when the fact is included. There needs to be Invitees for the Event for the record to show in reports.