Booking Manager portal has 3 types of availability, Realtime, Periodic and Rare and system by default gives you results for Realtime and Periodic boats.
For example if I search boats in Croatia (1.) on August 8th 2021 (2.), by default I receive 487 results (3.) for Realtime and Periodic fleets.
If I now place a check on Include yachts without availability confirmation (4.), I am expanding the search to include boat from Rare fleets.
With the repeat search for Croatia (1.) on the same date (2.) and included yachts without availability (3.) I receive 543 results for all available boats as the results now include Rare fleets.