11-11-20
Why all this hate people!? I've been using this add-on for a couple of years and it always worked properly! It stopped working for a week and you bombard the add-on with one-star reviews? WTF! Have some respect for the developer!

An issue was opened on github and the dev said that the problem is fixed and the addon will work as soon as firefox shows the green light.

For now, you can make the add-on to work by going in -> Manage Extension - Preferences - Open in -> New Tab