Hi I have had a similar problem, which I have reported to Airbnb but they have stopped responding to me now, saying I can update the calendar myself!
I have been setting trip length to 7 days minimum with a Saturday changeover day, for most of my weeks, as that is when my housekeeper is available to clean. However, I checked how my listing appears to guests under Preview, and for all of the weeks I had set those limits, only the Saturday ie one day showed as available! To guests it must appear I have only the odd Saturday free to book rather than the whole week. As I say, I have tried to explain this to Airbnb but they just tell me how to block and unblock my calendar. I have been doing this for 7 years now, so that is not the issue.
I am not sure guests looking for availaibilty rather than set dates would know this...potentially leading to fewer bookings.