Nested Navigation is not rendered to PDF when title is missing

[pyjoku]

I have been trying to get my SOP handbook working on mkdocs-material and I also want a printed version/PDF.

I am running on Windows 10/WSL (Ubuntu 20.04).

So i have nested folders and I realized when having a flat nav section all is being rendered to PDF. when I start setting up sections only the index file is being rendered but the rest of the files is being processed but they dont appear in the PDF.

while playing around I realized that when i add a title to the first file in the section it starts rendering the folder in the PDF again.

plugins:
  - search
  - localsearch
  - section-index
  - minify:
      minify_html: true
  - with-pdf:

# working code
  - Management:
    - Management: 04_Management/index.md
    - 04_Management/DOC0063_Personal.md
    - 04_Management/DOC0068_StellenbeDA.md
# not working code
  - Management:
    - 04_Management/index.md
    - 04_Management/DOC0063_Personal.md
    - 04_Management/DOC0068_StellenbeDA.md

So I am not sure if this intentional or unintentional behavior. 
I hope this might help others struggling with the same issue.