Ah, that!
Yeah, those are our generic thumbnails that we show when our plugin doesn’t find the appropriate images in your posts.
We updated and improved our thumbnailer (the one who aggregates thumbnails from your images) with our latest version which fixes a lot of irregularities that used to appear all across different blogs before, but on some sites (like yours, unfortunately) this isn’t the case. It seems as if it gets even worse, for what we are very sorry and already investigating what could be wrong.
In the meanwhile I would like to ask you for some help, if you find the time. Would you try to create a new (or any old one) blogpost with several different images, but if you could select/mark one as featured. Our plugin should pick up that one which is set as featured as a thumbnail, no matter what, but we are not sure if this is the case with the last update. Could you check that for us? We are very eager to find out, since we cannot replicate this problem on our side.
Let us know how it goes while we investigate what could be going on. Any help is very much appreciated!
Take care & I’m looking forward to your reply!
Best,
Silvo