@Boe7 It is also possible that the guest was new to Airbnb and their payment method was not approved or they were removed from the platform for some reason. I have found that when a person loses the right to use Airbnb, they are scrubbed from the system as if they never existed.
Keep up your spreadsheet and double check the status of a booking before you enter it. Requests to book can look very similar to booked and paid up, especially when the request temporarily blocks the calendar. P.s., you are not going mad. Welcome to the world of hosting through an OTA.