Unable to register to a course from the "course list" page

Taking as example the current version of INGInious at UCL:

1. Go to the "courselist" page.
2. Click on a not-yet-registered-in course (e.g. "LINMA1691 Théorie des graphes" as it was the only such course - but I don't take this course)
3. On the page, click on the "Enrol in the course" button at the right of the screen.
4. In the dialog, click on "Enrol in the course" again.
5. I was taken back to the course list page, and I wasn't registered in the course. Registration from the "My course" page (which is currently not the default page when logging in on the UCL site) works correctly however.