Category needs to have a ref in bundle menu in order for it to be collapseable

[Miepee]

Assuming I have something like this as my main.yaml:

- name: root
  sub:
    - name: foo
      ref: "/root/foo"
    - name: bar
      ref: "/root/bar"

and the _index.md for root only consists of this:

---
title: Root
geekdocCollapseSection: true
--- 

Then the Root category will not be collapseable.

[Robert Kaussow]

That is correct, the menu builder doesn't know that the page name: root refs to _index.md. This is the expected behavior.