I follow both accounts A and B.
A writes a long thread. In my home timeline, I see that B commented an hour ago, and A responded in turn soon thereafter. Given these posts in isolation, I don't get the context, so I click in to see the whole interaction, which brings me to the beginning of A's thread.
But scrolling down, I can not see a single comment to any of A's posts (which ended 4 hours ago?), nor A's responses.
I finally found the little arrow in the top bar that -when clocked - shows a lot of comments to one of A's posts in the thread. Not B's posts though: I assume they must have placed the comment on one of the other posts of A. But which, and how do I open that? I don't know.
Going back to the home timeline, I finally found one way of seeing the context: try to respond to B. That way I can see the interaction up to the posts that B commented on (and that A's thread continued a lot longer than I first saw).
The main problem with that is that the interaction involved a lot of images that now are thumbnail sized.
What am I doing wrong? What setting do I need to find and toggle?