I may not be seeing what you are (to me the threads seem the same), but is it possible your View Options got changed without you realizing it? I sometimes find that happens when I do a search.
If you want to check, go to the top right-hand area of the first post in the thread, just above the "Post #1" label. You will see a grey-blue box labeled "Options" with a drop down triangle. Click there and see what is highlighted. "Standard" allows all the responses to show automatically. It sounds like you are now seeing "Outline" maybe?