Multi-day all-day event in Bookings calendar does not block staff availability (single-day works)

Hi, that does sound like a Bookings behavior gap if a single all-day event blocks correctly but a multi-day all-day event does not. As a workaround, I’d create separate all-day busy events for each vacation day, or use the staff member’s time off/availability settings directly if that works better for your setup. Also make sure the calendar event is marked Busy rather than Free, and check the time zone on both the Bookings calendar and the staff calendar. Since you can reproduce it cleanly, I’d also report it through Microsoft support or feedback with the single-day versus multi-day comparison.