We're having an issue with epub generation in our installation of Manifold.  When a user clicks the "Enable EPub" button for a text, the "Disable EPub" toggle appears as expected, but the "Download EPub" button never appears. This is on version 8.1.1 of Manifold.  The texts are all still drafts as well, not sure if that makes a difference.  Any guidance on how to diagnose/address this issue is much appreciated.