@Tatjana6 hi, how are you? I have the same problem. Everyday at 3pm my calendar is blocked like unavailable despite it be absolutely available. Since July 27 I hold with a customer service that told me i have changed custome rules( that i have never done). So i checked custom rules and it was sat in "Various" instead "None" . I reset and i click in "None" and saved. The day after and the next follow days until today, when i login in, my calendar is unavailable for guest booking and the custom rules is again set up in "various"... So. I have two theories.
1* someone from one of the hosts in my town works on Airbnb and play to blocked my list because i started with the right foot.
2* Someone from the customer service plays God and have fun to make this kind of thing.
Nobody has access to my devices, nobody else has my email or password that i use with Airbnb and my other two calendars works perfectly.
I asked for economic compensations on July 31 because in the last conversatio with the customer service, they told me it is a kind o BUG in their IT system...so...i asked the compensation for do not make any money since july 27 and until today, nobody answer my question or fix the problem.
Good luck...