 https://addons.mozilla.org/ not rendered correctly compared to regular Firefox

On apparently every page on https://addons.mozilla.org, the list with other add-ons by 'developer name' is not shown correctly.
It shows an empty list instead of the list of add-ons.
See Mozilla's own add-on page as an example:
https://addons.mozilla.org/en-US/firefox/user/4757633/

The same issue seems to happen on all https://addons.mozilla.org pages.
