How to organize content in sub folders within posts?

[OCram85]

Hey folks,
I just tried to reorganize my blog posts to clean up a flat list like this:

posts\
    article1\
        index.md
        ...
    article2\
        index.md
        ...
    article3\
        index.md
        ...

...into something structured like this:

posts\
    article1\
        index.md
        ...
    article2\
        index.md
        ...
    releases\
        _index.md
        project-a-v0.0.1\
            index.md
        project-b-v1.0.0\
            index.md

If I'm adding the _index.md file in the releases/ path, hugo returns the lists of articles within this section, and also shows the article in the recent list on the home page. But it's missing in the main list on the posts/ (blog landing) page

If I remove the _index.md, hugo returns http 200 with a bank page.
This happens with the embedded dev server and deployed on a prod nginx.

So is there a way the blog post could list any nested articles even if there are multiple sections/paths? - Or maybe hugo should return a 404 error if someone browses to a section page without any content or index file?