Can't transfer epub3's to DRM-compliant e-readers

I work for a company that deals with digital lending in libraries and many of our subscribers are unable to transfer ebooks from Adobe Digital Editions to Kobo and other DRM-compliant e-readers: every time they try, they get a message that asks them to authorize their device (when in fact it's already authorized).

To be more specific: it seems to happen on DRM-protected epub3's and is happening both via Mac and Windows computers. I see that many users has had the same problem: does anyone have at least a temporary solution, given that this problem undoubtedly depends on Adobe? Thank you.