As David said, the Notification page is not working correctly. You can clear the notifications via a pc. I’ve just proven it again on my pc getting here. I’m using IE on a Windows platform. Scroll over the blue message indicator at the top, right side of the page and a list of the notifications will appear. As you select them, the notification number will decrease. Repeat those steps until the count is zero.
From a smartphone, log into the Forum and rotate the phone to landscape mode. There will be a head and shoulder icon. You might have to scroll up to see it. Tap on the icon and you will see an item that says notifications. This is where I think the problem is that David mentioned. Tapping on notifications gets you to the page that just tells you have messages, but they are not being listed.
If you have a pc, iPad, tablet or a Mac, you’ll have to use it for the time being.