Hi Christian,
Indeed, there was an issue there with the page editor. When the plugin tried to get the content of the shortcodes, they were returned completely empty. It turns out, that for some reason the page editor requires the global $post object to work correctly. I had to make an adjustment directly on the search code to fix that issue.
Now it should have the contents indexed correclty. I will also make sure to include this fix in the upcoming releases.