Does that happen on chrome? I wonder what would happen if you swap out the user agent and have that issue. Edit: It's working now just fine, even if I am not s

Does that happen on chrome? I wonder what would happen if you swap out the user agent and have that issue. Edit: It's working now just fine, even if I am not signed in. Like they suggest below, it seems like that is Twitter being actively malicious to web users, and not Firefox.