Zoho Documents/Writer Offline still not working

Zoho Documents/Writer Offline still not working

Hi There, I am testing a paid version of Zoho Docs and set up Desktop Sync on my Mac which works great.  When I go offline I can open any MS Word docs which synced and edit them fine, but cannot edit .zdoc files offline and it opens my browser (Google Chrome) and just says I cannot edit because I am offline.  I have also tried Safari and Firefox as my default browsers and all show the same problem, is there a work around here? How do I edit .zdocs offline? thanks,