Missing traversal data

Expected behavior and actual behavior

According to Middleman: The Sitemap, I should be able to access Middleman::Sitemap::Extensions::Traversal data using the current_resource variable.

However, while this variable is available in my template, the parent is usually nil, while children and siblings are empty arrays.

Steps to reproduce the problem (from a clean middleman installation)

Template:

Path: <%= current_resource.path %>

Siblings: <%= current_resource.siblings %>
Children: <%= current_resource.children %>
Parent: <%= current_resource.parent %>

Output:

Path: foo/index.txt

Siblings: []
Children: []
Parent: 

Additional information

• Ruby version: ruby 3.2.2 (2023-03-30 revision e51014f9c0) [x86_64-darwin22]
• Middleman version: Middleman 4.5.0
• OS version: Mac OS Ventura Version 13.5.1 (22G90)