The new external log in option should put an end to all log-in issues (I hope). In-app log in works for most people. For the few where it does not work and for people who are uncomfortable typing in their password, there is now external log in. Although it is bit more cumbersome, by using audible/amazon log in directly in your browser it ought to work for everyone.
Libation is a free, open source audible library manager for Windows. Decrypt, backup, organize, and search your audible library
I intend to keep Libation free and open source, but if you want to leave a tip, who am I to argue?