Using Page Resources from non-index

support
3

It should not. A branch bundle’s resources are not available to a page within the bundle.

content/
└── posts/
    ├── post-1/
    │   ├── b.jpg
    │   └── index.md  <-- leaf bundle
    ├── post-2/
    │   ├── c.jpg
    │   └── index.md  <-- leaf bundle
    ├── _index.md     <-- branch bundle
    └── a.jpg  <-- available to the branch bundle, not to other pages within the branch

If you use the same image in multiple places, and you reference the images using Markdown (not HTML as you show above), consider placing them in the assets directory. Then you can enable Hugo’s embedded link and image render hooks to properly resolve the image destinations.

This might be useful:
https://discourse.gohugo.io/t/markdown-style-images-with-full-path-when-baseurl-includes-subdirectory/52487/2

If you really, really want to make a branch bundle’s resources available to pages within the bundle, you can override Hugo’s embedded link and image render hooks as follows:

layouts/_default/_markup/render-image.html 
{{- $u := urls.Parse .Destination -}}
{{- $src := $u.String -}}
{{- if not $u.IsAbs -}}
  {{- $path := strings.TrimPrefix "./" $u.Path -}}
  {{- with or (.PageInner.Resources.Get $path) (.Page.Parent.Resources.Get $path) (resources.Get $path) -}}
    {{- $src = .RelPermalink -}}
    {{- with $u.RawQuery -}}
      {{- $src = printf "%s?%s" $src . -}}
    {{- end -}}
    {{- with $u.Fragment -}}
      {{- $src = printf "%s#%s" $src . -}}
    {{- end -}}
  {{- end -}}
{{- end -}}
<img src="{{ $src }}" alt="{{ .Text }}"
  {{- with .Title }} title="{{ . }}" {{- end -}}
  {{- range $k, $v := .Attributes -}}
    {{- if $v -}}
      {{- printf " %s=%q" $k ($v | transform.HTMLEscape) | safeHTMLAttr -}}
    {{- end -}}
  {{- end -}}
>
{{- /**/ -}}

Compare the above to the original image render hook.

layouts/_default/_markup/render-link.html 
{{- $u := urls.Parse .Destination -}}
{{- $href := $u.String -}}
{{- if strings.HasPrefix $u.String "#" -}}
  {{- $href = printf "%s#%s" .PageInner.RelPermalink $u.Fragment -}}
{{- else if and $href (not $u.IsAbs) -}}
  {{- $path := strings.TrimPrefix "./" $u.Path -}}
  {{- with or
    ($.PageInner.GetPage $path)
    ($.PageInner.Resources.Get $path)
    ($.Page.Parent.Resources.Get $path)
    (resources.Get $path)
  -}}
    {{- $href = .RelPermalink -}}
    {{- with $u.RawQuery -}}
      {{- $href = printf "%s?%s" $href . -}}
    {{- end -}}
    {{- with $u.Fragment -}}
      {{- $href = printf "%s#%s" $href . -}}
    {{- end -}}
  {{- end -}}
{{- end -}}
<a href="{{ $href }}" {{- with .Title }} title="{{ . }}" {{- end }}>{{ .Text }}</a>
{{- /**/ -}}

Compare the above to the original link render hook.