Twice this week I had this issue with special offers.
The guest clicks on the offer, and the special offer price disappears the higher listing price shows up.
They have to click all the way through to the payment page, to see the special offer price again.
Airbnb has now automated their CS chat service to such an extent, it was impossible to get help on this until finally I got this robot response.
I almost lost 2 bookings due to this so it would be nice if they made it easier to find this information.
IF YOU RECEIVED A SPECIAL OFFER from a host and when you use the "Book Now" link, you may see the original higher price at first. Please click through to the final payment page, you should see the special offer price. If you do not, please try the following to correct the price.
FROM THE APP
Please refresh the app or quit the app to clear your phone cache and relaunch the app. Then access the Special Offer from your email or inbox.
Go all the way to the very last screen where you confirm the price and payment method. The correct price should appear.
If this doesn't work, please try using a computer or mobile browser.
FROM A COMPUTER
Access the offer link in your Inbox.
Clear the browser cache and relaunch the browser.
Now go all the way to the final payment confirmation page where you should see the correct price.