Ask HN: does Hacker News Semi-block Tor?

Does Hacker News semi-block Tor traffic? I notice this recently that when I tried to log in using Tor and it won't let me. This URL https://news.ycombinator.com/null shows up on the address bar. It could be a bug, but this has happened many times.

At the same time, all posts made using this account is not visible anywhere else to any of my friend who are NOT using Tor. Is there some kind of sensor ship at hacker news? Given that we are discussing so many politically sensitive topics, I would really like to know.