I ran a test with the plugin. What I found was that it created a second image on each excerpt. This second image was a copy of the post “Featured Image” for every post except the most recent post. On the most recent post it displayed a copy of the image from the next oldest post, which is what you described. This duplicate image issue is a known problem on the plugin support forum. When I deactivated the plugin, all the duplicate images were removed and the page appeared normal. I’m not sure why all the images “disappeared” on your site. Based on the results of my brief (and very unscientific) test I might guess that all the images you’re seeing were the duplicates generated by the plugin, and your “Featured Image” images weren’t being displayed. When you deactivated the plugin it no longer generated the duplicate images so now you’re not seeing any images at all. But that’s just a guess.
Based on your theme settings and other plugins you have installed there could be other conflicts as well. If you can’t isolate the problem by changing other options or deactivating other plugins, I’d recommend restoring the site from a backup that you know was working normally prior to having installed the plugin.