Adobe Digital Editions 4.5 not working with Mac OS X Catalina.

This exact thing is happening to me. I hadn't realized the cause of it was updating my Mac, but now that I think about it, that is when the problem started occuring for me as well. I've also tried all the things you did and called B&N for Nook help but they said it was an Adobe problem and that I'd need to figure out how to authorize the device on my own. Anyone who's solved this problem I'd be interested to learn how! Missing my Nook during social distancing :'( ...

Bonjour, 

J'ai un problème du même genre. Depuis la mise à jour MacOS 10.15.2 Catilina sur mon MacBook Air, un livre acheté aux éditions Le Robert disparaît d'Adobe Digital Editions chaque fois que je ferme le logiciel (l'option "ajouter à la biblotèque" ou "copier dans ma bibliothèque"est en grisé et donc inacessible)  : je dois donc le retélécharger chaque fois, ce qui suppose d'avoir une connexion Internet à ce moment-là, mais surtout je perds tous les signets que j'ai mis sur ce livre et qui me sont primordiaux car c'est dans le cadre d'un travail. 

Robert ne peut pas m'aider et me renvoie vers le service Abode, qui est injoignable au téléphone (des heures à attendre en vain en ligne). Quelqu'un a-t-il une solution ? Merci d'avance

Hello,
I have a similar problem. Since the MacOS 10.15.2 Catilina update on my MacBook Air, a book bought from Le Robert editions disappears from Adobe Digital Editions each time I close the software (the option "add to the library" or "copy to my library "is grayed out and therefore inaccessible): I must therefore redownload it each time, which implies having an Internet connection at that time, but above all I lose all the bookmarks that I put on this book and which me are essential because it is within the framework of a work.
Robert cannot help me and refers me to the Abode service, which is unreachable on the phone (hours to wait in vain online). Anyone have a solution? thank you in advance

I'm reposting a response here -- thought it might be helpful after spending hours trying to find a solution to this same problem.

I'm on Mac Catalina, using Adobe Digital Editions 4.5 to manage library books on my Kobo Aura.  I began getting the "you aren't authorized" message suddenly after being able to use ADE 4.5 successfully with Catalina for a few weeks.

I tried all the device deauthorizing/reauthorizing/ADE uninstall/ADE reinstall/factory reset suggestions and nothing worked UNTIL I tried deleting some of my old e-book files I no longer wanted (stored in Documents/Digital Editions). Next I renamed the Digital Editions folder, and as suggested by another Kobo user, went to the library site and downloaded a random book I'd never downloaded before. That book opened perfectly on my Kobo, as did all the books that previously hadn't opened because of the authorization glitch.

This approach makes no logical sense to me, but it did work in my case. Hopefully it will work for others.

Good luck!

Having the same problem.  Neither Kobo nor Adobe has been helpful to solve the problem.  Super annoying. If anyone has found a solution, please post.

I am having a similar problem. I have a new MacBook Air. I have followed a similar path as the above and my kobo is still not authorized. Help