Alex,
Having the same issue. We have our calendar set to 9 month availability window. However we are noticing that as the calendar moves, those dates are not opening up, they are staying blocked. Even as we tried to chance the window to 12 months, just as a test, those dates are staying blocked.
Conversations with airbnb support go nowhere, as they dont understand the issue, however in some basic research we have seen other hosts posting about this and it appears to be related to the software update they rolled out toward the end of 2023.
If anyone has a similar issue, or insight please add on...
Thanks,