Digital editions will not retrieve any books (iMac)

Hello,

I got some issues with downloading the books I lend from the public library.

The download starts.... and never finishes. Although the book is copied already in the "digital editions" folder.

So I have to force digital editons to quit but on the next start my book isn't there just the download link to the public library.

I'm running digital editions on a iMac with macOS Sierra 10.12.1

Any suggestion would be very much apreciated.