The notification no longer goes away on each post unless you click on each one
Can you check that once you've cleared them, that does not continue? And... of course a clearing of your phone cache. Maybe a browser refresh, etc.
The new alert system allows you to "mark a conversation unread" so you can remind yourself to come back to it.
The little dot on the right is what marks them. If you press that dot, it will mark "unread". Press again, it unmarks.
I have noticed on my mobile phone I've hit those accidentally. Now that I am aware of this, I can avoid it.
There might be a setting I can modify and I will look into options. But, the ability to mark unread is a feature that could be useful.
Lastly I'm using FireFox. It's possible a particular browser is not playing nice. Can I ask the browser of your mobile?