Download Doesn't Start - Workaround Exists

My download is never starting, but I've found a way around it. I've looked at all the other bugs that appear related, and none of their solutions apply.

When I click the SCAN button, a new reader window opens, and the button changes to "Preparing". Nothing else happens. If I click to the reader window and then click on the extension, I get a message Reload page to use this extension. If I click the Reload button in the dialogue, the page reloads, the scan starts, and I eventually get a Save As dialogue box. When I save the file and return to My Books, the button next to that book is now RESCAN.