Hi @Rory15
If the dates are still available in your calendar my best guess would be that the issue is with the guest rather than with your listing. It is possible that this guest profile has been cancelled for some reason and they are no longer allowed to book with airbnb. Another reason could be that they tried to use a payment method that was invalid like a stolen credit card or perhaps the 24 hour window for them to submit payment expired and the ability to book within the time the property was on hold for them had expired.
In my opinion, the message reflects that the guest has not met the criteria to be able to book your property - you do not get an explanation why. This is just a courtesy message advising you that the booking did not go through. If your calendar dates are blocked and this is not because of another airbnb guest who made payment faster and confirmed a reservation at your property, you must contact airbnb as this falls outside the scope of "normal" site behaviour and is likely something that has not been experienced by the people who have seen your post.
I would assume that you would have checked that your listing is live and all is okay on your end. If your calendar is not blocked because of this I would not worry about it. If it's blocked and you find out why, please let us know so that we can help others in this situation in future. Thanks Rory.