“Hide Read Posts” - not a toggle?

I’ve got “Mark as Read on scroll” turned on, and when I come back to Narwhall I’m seeing many already read (or scrolled) posts.

I discovered the “Hide Read” menu item, but it doesn’t seem to be a persistent toggle

What I’m seeing is all the read posts on screen go away, and a scroll or two later more read posts appear.

I tap “Hide Read Posts” again and the cycle repeats.

Is there a permanent toggle in Settings I’m missing, or is that item supposed to be more permanent?