Cannot reply in private message

Hi, during a private discussion with @DELL-Cares I'm not able to reply anymore. I can't see Reply button at all in our thread (in my private messages). Additionally I cannot switch between threads - I can only see last message. It looks like an HTML/JS issue on the page. I'm using Windows 10. I verified Chrome and Edge browsers. Every components is up to date. I'm using XPS 9570 so it shouldn't be hardware problem Any idea?