Have you tried to do this through Firefox/Chrome? I’m not sure Tor developers are looking out for this use case. Firstly, X (Twitter) uses a .com domain not .onion and secondly you lose all your privacy benefits if you log in
I haven’t tried reproducing it on Firefox or Chromium based browsers yet. I mostly use Mullvad Browser and came across the issue using it. I was able to reproduce the issue on the Tor Browser so I guess there’s nothing specific about the Mullvad Browser that causes the issue.
I don’t know how to close a topic on Discourse but I’ll find how if people on this forum thinks this is out of scope