Seems that things may have moved on a little since the original post. I had many epxeriences of this where, upon attempting to accept a reservation reequest, a dialogue box popped up informing me that the payment hadn't been successful and offering me the option to accept the request and wait up to 24 hours for the payment to complete, or to decline the reservation. In every case I took the decline option and in every case the reservation was put into an awaiting payment status.
Every time (after the first one when I expected the decline option to do just that) I took screen shots and called Airbnb. Each and every time (over a periodm of maybe 12 months) everyone at Airbnb denied all knowledge of this "bug" and the best that I got out of them was that I ought submit feedback.
On the last occasion that I received a booking request where the guest had some payment problem, upon accepting the request it was immediately put into an awaiting payment status.
Airbnb tell me, in effect, "thems the rules" and that is how it is, refusing to cancel the reservation.
So now, you have the 24 hour cancellation policy forced upon you as a host, you now have 24 hours for the guest to sort out payment forced upon you - at this rate perhaps we should all register as charities.
Airbnb seems to think it is perfectly acceptable to behave in this manner, even if guests know they are required to pay upon making the reservation request, probbly because, as we all know, it's all about the guest with Airbnb