I can't log in to https://bugzilla.opensuse.org/ or https://forums.opensuse.org using Firefox. It does work with Konqueror.

Once the https://login.microfocus.com/ page comes up, after pressing "Login", the address bar flashes yellow and returns me to the same page.
This might have something to do with third-party cookies, but I can't find any information about how to add them as exception in Firefox. I'm blocking third-party cookies in Firefox.

On the other hand, if I disable cookie blocking, it doesn't work either. Any pointers?