black book covers on device

After downloading books from ADE to my device the book covers are blank.  This happens with both purchased books and library books.  I have uninstalled and reinstalled everything, twice.  I have contacted the device manufacturer (Pocketbook) and the library, they both tell me it is a problem with ADE.  I have read that installing an older edition, 3.0 may fix the problem, but when I do that I recieve a message that the software is to old to run on my new imac. I have contacted ADE and they told me that the software is end of life and has limited support.  WTH?  Clicking blank cover after clank cover trying to find my book is maddening.