Can't tag user in Talk file sidebar

What I open the details sidebar for a file in a shared folder, I have the option to use the comments or chat sections. In both there is a feature to @ a user to reference and notify them. While this works as expected in comments, it does not in chat. When I type @ in chat, there is no pop-up and even if I type the user’s name, nothing happens. On the other hand, this functionality works as expected in comments.