Hello! 

As far as I see when user opens the page with talk and this talk was not created yet then talk is created and this user is added to the talk to the participants list, but if you the talk already exists and user opens the page with block, then he should send at least one message to be added to the participants list. 

I have added this problem to the bug list https://github.com/unaio/jot-client-una/issues/184 and fix it in the nearest update.