I had the same thing happen. The Preview sowed 2 days prior as blocked on 2 of my bookings, yet on my calendar it showed available. I had no prep days set either. I contacted AirBnb who first requested if they could phone me which they did. (Was impressive). She determined this was a glitch but the good news was that it did not show this way to the outside world, only on my Preview. I tested it from my husbands phone to be certain and she was correct. It still appeared open to the public search. Hopefully they can fix this but in the meantime, know that your preview may not be accurate.