Automatic insertion after HTML object doesn’t work with Ajax loaded elements

I am trying to insert a block after an HTML object called “div.classname”. The HTML object appears after every of my articles, and I am using Ajax to autoload the next posts.

In post #1, the block loads fine. But then, I scroll down to posts #2 and #3, where the block is not loaded. The classname of the HTML object remains the same. Interestingly, all the other blocks load fine (I am inserting those other blocks after specific paragraphs). Any way to work around this? Is it perhaps a bug?

Btw, extremely useful plugin, thanks! I love it.