FYI, since the last update to the forum the private message indicator is sticking even after reading all unread messages until browser cache is refreshed. I've observed this in both FF and Chrome so it's not browser specific. I also don't use any script blockers.
I haven't noticed this.
The counter disappears when I read my Private Messages.
Using Firefox with just uBlock.
Now I have a new unread reply to a private chat that hasn't triggered the usual dot at all. It is highlighted in green in the list though