I was able to view my online documents after Adding the merchants website to Firefox Permission Exception for Pop Ups, clicked "Allow" and Clicked "Save Changes".   

FF does not block pop ups when box checked. Firefox Permissions yesterday blocked Pop Up for viewing my online documents with message "Permission to access file denied" . I was able to view my online documents after Adding the merchants website to Firefox Permission Exception for Pop Ups, clicked "Allow" and Clicked "Save Changes". Next day, the Merchants website no longer appear in Permission Pop Up Exceptions Window, its now empty. And now I am no longer able to block viewing my online documents as Pop Ups - my online documents are no longer Blocked when I click the "View" button -even though Permission Block Pop Ups box is checked and no websites appear in Permission block Pop Ups Exception Window. I have tried a few suggestions from Reddit which did not solve the issue. Please help.