Okay I see the issue.
If the post is long enough to include a middle ad…..it drops the last ad automatically, even if the middle ad has no code in it and the last one does.
In my scenario, I am only using the last block. I am not using the lead or middle blocks.
I just saw in the drop down you can Suppress certain blocks individually. I think you should pull this option out into its own checkbox or radio button. Might be a little more intuitive that way.
Otherwise thanks for the plugin. I will definitely consider investing in the Pro.