…when I click on Forum I can’t see anything in New, Latest, my own DMs, etc. to click on. What am I being notified about?
In the forum, if you click on your user icon in the top right corner, you’ll get a list of notifications:
On the right bar, the category where you have at least one remaining notification is shown. You can click it to see what it is.
Or you simply click the button on the bottom:
To get the full list of notifications and then “Dismiss all” to dismiss them all without checking them.