Clicking the Mark As Read button, or selecting Mark As Read from the menu, has no effect for certain feeds. Don’t know what triggers it. I’ve observed the problem on multiple feeds, with no clear relationship.
I have a screen capture video demonstrating the problem.
I have same problem. And it’s actually worst for me because on some feed when I click on “Mark As Read” then bunch of all items will appear as unread.
It seems to be working fine for “Unread - Newest” setting but it’s not working of me with “Unread - Oldest” which I’m normally using. So I think it’s problem that was introduced in version released during this weekend which changed how “Mark As Read” works.