Hello Everyone,
It's sad to hear you all have the same problem and virtually no reply from AirBnB forum moderators, at all! NOT a good service, isn't it?... Anyways, great news is that solution is already there and working, you only need to know how.
So cutting long story short, no matter where you are based in the World go to your hosting account and navigate to 'Payout preferences', find 'Payout method' button and simply follow the steps. Make sure you choose your country from a drop down at the top of the page and not a default one(different countries, different banks - different IBAN length). Also, try to add the payout method on your desktop/laptop computer as opposed to a mobile app.
In fact when I have just set it all up after having an uphill struggle the other day on my mobile phone, I was given two options by AirBnB partner's pay gateway WorldPay: payouts directly to my bank account via sort code and acc. number and IBAN. Both worked form me just fine on my desktop computer.
Hope this helps.
All the best and good luck making big bucks!