You're speaking of 2 different issues. I have a permanent red notification circle I can't get rid of. I even navigated to the Activities section under my profile and clicked on each of my post for the past 4 months...but the circle will not clear.
There is also an issue with late red circles. If I notice a topic has changed since I had last contributed to it (bold font with a name of a new contributor), I will not get a red circle. Nonetheless, I click on the topic to read the post and the bold font will return to thin font. The bold font notification works.
However, later in the day, there will be a late red notification circle of that "new" post...even though I had already read it.
It's just broken and indicative of no quality assessments at Cox.