I updated the theme to the latest version. The repeating posts and the missing featured images continue to be an issue. I think I know a bit about what is happening. The theme uses an infinite scroll to show all the posts on the home page. It doesn't implement it in a way that the WordPress dashboard recognizes it. The WordPress dashboard doesn't have a way to turnoff the scroll. There also seems to be some conflict between selecting the number of posts that appear on the page as to the number of posts the theme loads at a time before the next sroll loop. I have set the number of posts equal to the number in the theme template. Not sure why that stops the duplicates but it does. It also limits the number of posts that can show a featured image. This post is a summary and a test of those theories. Regardless of the outcome I think I need a break.