Oh it looks like a problem with one of my plugins https://github.com/barisusakli/nodebb-plugin-twitter-hashtag.
Confirmed, that was it, thanks. I hadn't realized that that had gotten installed.
What is the main point, when you visit Unread section, to open topic from the first message?
One possible solution: Add button (btn-default) near title, with clear message (go to unread message)
Have much more possible solutions? - add settings to the ACP. Every community will select most UX friendly for them.