Airbnb just changed its policy regarding the cancellation towards the hots. On my listing, the policy is flexible so the guest can cancel 24h before the arrival to allow them as much time and flexibility. However, now @Airbnb cancels bookings less than 24h prior the arrival without any reasons and no partly refund as it should be !
Be aware, never happened before to me and that’s a new thing now !
As far as I can see, the wording on the Flexible cancellation policy hasn't changed, i.e. if the guest cancels less than 24 hours before, you are supposed to get paid for the first night.
Interesting that you say Airbnb, not the guest, cancelled. Could the guest have claimed extenuating circumstances? If so, then Airbnb will override whatever cancellation policy the host has is place.