I use g h to go to the list of latest threads. I use j to navigate to a thread that has more than one unread comment. (That thread will be in black rather than grey to indicate that it’s got unread comments.)
I hit Return on that thread, which teleports me to the first unread comment in that thread. Good. I use j to read all comments. After the last comment, I keep hitting j to navigate past the suggested articles, to the bottom-most article on the page. (I do that just to be really sure that the last comment is marked as read.)
Now I hit g h to go back to the list of latest threads.
But that thread is still marked as unread! When I open it, I get teleported to the last comment in the thread.
If I then g h once more, then the thread is marked as read on the list of latest threads.
Can you reproduce it?
- I believe it doesn’t matter whether I use
g hto go to the list of latest threads, or use another method. - I’ve tested that it doesn’t matter whether I use
jto select a thread with unread comments, or I just click on it. - I’m unsure about the
jscrolling, though. I should have tested the space bar, the cursor keys, the page down key, and the two-finger swipe to scroll on my Mac. But I haven’t. I guess I really likej…
Update: After saving the above text, I thought I could try other methods to scroll, so I went through and searched for some threads with more than one unread comment. But I couldn’t find any. So I think I will have to wait for some content to arrive on the site 
I may not be able to work on this for the next two weeks, though.