Hi. They all have images because I have had to set the Featured Image on some of them to achieve this.
I am sure this was working up until a few days ago.
What is very odd is that I have just tried the same thing on my own domain and I have the same issue there too – if you go to tonystoyle.co.uk/radleyvillage I have just duplicated the latest post (which has an image), the new one does not! It appears in the Post though. Very odd.
Thanks.