Clicking on "Join & submit" after completing the second and third quiz of this course, I have a popup message that says that I have already joined this channel and my answers aren't submitted.

The consequence of this is that I do not progress on the course.

Actually it seems like the button isn't changed to "submit answers" as it should (I have checked that on Chrome).

I should precise that I'm on the latest Firefox version if this has something to do with the problem.