I can't reproduce the described misbehaviour. I also can't reproduce it in Milo's forum, which runs with the actual version 2.3.7.
I am not sure which version we have because I am not the forum owner. As an admin, I could only found the property "version" of value "2.3".
On the other hand, some sources were replaced by Milo's version... I don't know... maybe it had an unpredicted impact.
I'll try to survey our users if all of them have this problem. Maybe it's browser dependent?
I personally don't use the "Refresh", because of the point 2 below. After refreshing, all posts are unread, I find it quite distracting.
1. It reloads the main page.
2. It resets the browsers "list" of visited links for forum internal links (what's IMHO a misbehaviour by itself).
I think you didn't mention: 3. the "new" style modifier is cleared from posts and threads after "Refresh". This is why some of our users use the refresh anyway. After refreshing, the forum page contains no "new" threads and posts (visually: no red borders and arrows). I assume these users find it more readable to look at the icons than at the subjects. As I said, I don't belong to them.
Anyway, this behaviour of "Refresh" seems inconsistent to me. It clears "new" posts and threads? OK. But it also clears "read" style modifier and this is not intuitive.
From what you wrote a few days ago, I suspect that the list of read posts is kept somewhere and what is not in the list, is treated as unread. "Refresh" clears the list, right?
Maybe it should be done just the way round? To keep the list of unread posts and treat all the rest as read?
A few days ago I also considered some more solutions to this problem. I hope you found it useful in the future development.