Could it be something like https://discussion.fedoraproject.org/t/registration-difficulties-on-chat-fed...
TLDR: matrix is supposed to show you a 'agreement' thing when you first login to accept, somehow for this other user it got in a weird state where they were not able to accept it or do anything else because it wanted them to accept first.
If thats the case, I can ask our matirx contacts to fix your account.
I suppose also you could make a new account and try with it to confirm you get the agreement and things work with it?
kevin