Advanced Analytics is a premium feature available to Pro users only. Contact us to discuss activating it.
The definition of occupancy in Advanced Analytics is the number of booked days (with a confirmed reservation) divided by the number of bookable days, that could have been booked (could have had a confirmed reservation).
As explained in this article, a listing's calendar can have blocks that stop a date from being booked. By default, dates with these blocks are not considered bookable. Contact us to add any of them to your Advanced Analytics so that dates that have them are considered bookable.