Hi @Todd-And-Heather0:
There have been known glitches when AirBnB is doing system updates (2...3 times a week).
People are reporting unintended changes to the calender. Sometimes AirBnB compensates, mostly not.
>It is not something I ever change.<
Unfortunately YOU SIGNED the AirBnB agreement, so YOU have to keep your listing ALLWAYS update. I recommend to check 2..3 times a week for blocked or unblocked dates, prices, conditions.
Sorry... no better information.
I strongly resommend to untick the Immediate Booking option! So you will always see the reservation, price etc. and can check REAL availability PRIOR to accepting the reservation!
Regards
Michael
Saludos
Michael