Using the featured image has worked in the past, but any new posts made recently don't display the thumbnail. The older posts still work, just not new ones.
I am using the Streamline_30 theme. I tried switching to another theme and the problem doesn't exist, so clearly the problem is with the theme, but I'm not sure how to fix it. I don't understand how it can only be a problem with recent new posts.
website is: jamespaulcorreia.com
Any help would be greatly appreciated.