Something sure has changed. I can't see the images now.
If you for example quote someone (by hitting the quote button), the link will contain a sesc= section, hence images are deactivated in the topic summary.
If you write a straightup reply without quotes (by hitting the reply button), the page you're on will not have a sesc= section in it's link and you will be abled to see images in the topic summary.
so maybe this feature was added to safeguard the forum?
I don't think anything changed in this area on the forum's end. Links and images are disabled whenever "sesc=...." is in the URL, since this is sensitive info which otherwise might be transmitted in the referrer.