I found the solution to this finally (for me at least)z. It seemed to revolve around having different Facebook logins in the past. The mobile app was trying to link to a Facebook account email no longer used and the mobile app forces the login. When using the desktop site, it linked to the appropriate Facebook email.
Solution:
1. log out of the mobile app.
2. Clear your browser cache.
3. Contact customer support and tell them to deactivate the WRONG email for the reason explained above.
https://www.airbnb.com/help/contact_us/channel
4. Once they confirm this is done, redone load the mobile app.
5. Login with the approprIate email.
I hope this helps!