Microsoft Bookings double-booking staff despite busy calendar entrie

This kind of double-booking usually happens in hybrid setups because Microsoft Bookings relies on Exchange Online to check a person’s availability. If a staff member’s mailbox is still on-premises or if free/busy sync isn’t working perfectly, Bookings may not “see” their busy times and will allow overlapping bookings. The settings you’ve already checked are correct, so the issue is likely with the hybrid sync. If possible, try testing with a fully cloud mailbox to confirm, Bookings generally works best that way. In the meantime, you could also use tricks like adding buffer times or manually blocking slots to reduce conflicts until the sync issue is fixed.

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