Booking close my date while my calendar available

Hi everyone,

I want to share this to know if someone who got the same problem like me.

My room open for rent for 4 months and I wonder why it's cheapest price without noticing from guest.

4 months pass by.

today I figure out,

My calendar is available. No close, no block date. But one of my guest who want to book my room and they said they can't book because no room left for them.

and here is what I see.

I sent message to ask. I need explaination. This is reason why booking.com automatic block my room without permission when I run my own business