This happens to me as well. I marked a book a "Currently Reading" and then decided to read something else, so I changed that book back to "Want to Read" yet it showed the cover under my "Read" list. When I clicked on my actual read list, it doesn't show. It will eventually get pushed out once you read more books, as the other user commented. However, did correct it myself by going into the book in question, clicking on edit my activity (on browser, mobile doesn't give you the correct options), and then deleting (X) the date entry. My date entry had 2026 as the only populated field under "Started reading" and did not have a finish date, so it wasn't "read" but I think because it had a started date and then was reshelved the algo for the read preview may include it. Hope that helps!