That is really bizarre. What happens when you go to https://unitedfederationofpla.net/s/members/darian-harder/notifications ?

In the app, in the left menu, My Profile – and you should see a globe with notifications count

Also, be sure to leave the “Notify me of follow-up replies via email” box, which should be automatically checked.

One final thing you can do is hit the “Subscribe” button on every Forum that is of interest to you