Topic title should really be changed, as a refresh of the index is enough to lose notification badges. You don’t have to view any forum.
In the video below I’ve just lost a notification badge. So I explore the app and find it under the All tab. Finally, I go into the forum (where’s there’s still no badge) and find it under the bell notifications view, where I can tap on it.
Still happening in the latest TestFlight beta 1.8.12 (421)
In the screen below the list refreshed and a notification badge on forum 2 disappeared. We can still see it, and that it is unread, by tapping on the bell and selecting the “all” tab.
This is a very old bug, three years is a long time, thank you for sticking with it and for still using the app. I am very very sorry to have taken so very long to find a fix. The fix is not very complicated, we were resetting the seen notification id but we were only doing so for sites where push notifications aren’t enabled (i.e. sites not hosted by Discourse). I don’t have a good excuse, I just didn’t pay close attention to the right bit of code when I first looked into this.
Anyhow, I very much hope this is fixed in the beta. As usual, let me know if that’s not the case.