Not working with private posts

It seems like the plugin can’t handle private posts. For testing purposes and to adapt my style.css I created a couple of private posts and added them to a article serie.

• The serie is shown correctly when editing the post
• The serie is shown correctly when listing posts
• I can filter the posts with the serie
• When I list the series the serie shows 0 posts (even though there are 4)
• Displaying a post the plugin shows “Part X of 0 in serie …”
• The box containing all posts within the serie is empty
• The Series Meta is not showing

I tested the same setup on another WP instance, as soon as I set a post where the plugin worked before to private, it half vanishes from the serie.

https://www.ads-software.com/plugins/organize-series/