Difficulty returning library eBooks

I have been using Adobe Digital Editions for Library ebooks via borrowbox and Cloud

I am still able to access books from library and open them in Adobe Digital Editions but Today I noticed I am unable to return to library and recieve this box message" Unable to return error returnng item, please authorise your computer first"

I contacted Adobe support and I have erased and reauthorised on this computer before posting this message. In Help The authorise computer command in gray so I cannot access/

Any suggetions please? Thanx