All of a sudden this blog started showing only one post on the homepage. No matter what setting I changed only 1 post showed on the blog. The problem was the last post had a 'base64' image in it. Which means instead of a normal pic the image was made up of the CODE used to render the pic. When this happens Blogger will only show 1 blogpost on the homepage. The solution for me was just to take a screenshot of that image, then re-upload it to the blog post in question. After that it was fine. In fact when I opened the problem post I got this message at the bottom left :
