Can you spot in this below, what causes the partial not be found, despite the names being unique and only present in that file ?
render-image.html
{{ if (or .Attributes.cite $.Title) }}
{{ partial "partial/defaultFigure" . }}
{{ else }}
{{ partial "partial/defaultImage" . }}
{{ end }}
{{ define "partial/defaultFigure" }}
<figure {{with .Attributes.id}}id={{.}}{{end}} class="{{with .Attributes.class}} {{.}}{{end}}">
{{ with .Title }}<figcaption>{{.|$.Page.RenderString}}</figcaption>{{ end }}
{{ partial "partial/defaultImage" .}}
{{with .Attributes.cite}}<cite>— {{.|$.Page.RenderString}}</cite>{{end}}
</figure>
{{ end }}
{{ define "partial/defaultImage" }}
{{- $img := "" -}}
{{- $destination := urls.Parse .Destination }}
{{- if $destination.IsAbs }}
{{- $img = resources.GetRemote $destination.String }}
{{- else }}
{{- with .Page.Resources.Get $destination.Path }}
{{- $img = . }}
{{- else }}
{{- $img = resources.Get $destination.Path }}
{{- end }}
{{- end }}
{{ $Type := "video"}}
{{ if eq $img.MediaType.MainType "image" }}
{{ if in $img.MediaType.Suffixes "svg" }}
{{ $Type = "svg" }}
{{ else }}
{{ $Type = "image"}}
{{end}}
{{end }}
{{ if eq $Type "svg" }}
{{$img.Content}}
{{ else if eq $Type "video" }}
<video autoplay loop muted controls poster><source width=2OO src="{{ $img.RelPermalink }}" type="video/{{path.Ext $destination.Path}}">There should have been a video here but your browser does not seem to support it.</video>
{{ else }}
<a role=presentation target="_blank" {{with .Attributes.link}}href="{{.}}" rel="nofollow external"{{else}}href="{{$img.RelPermalink}}"{{end}}>
{{ $src := slice }}
{{- $smallest := "" -}}
{{- $very_small := "" -}}
{{- $small := "" -}}
{{- $medium := "" -}}
{{ if gt $img.Width 200 }}
{{ $smallest = $img.Resize "200x q95" }}
{{ else }}
{{ $smallest = $img }}
{{ end }}
{{ if gt $img.Width 400 }}
{{ $very_small = $img.Resize "400x q95" }}
{{ else }}
{{ $very_small = $img }}
{{ end }}
{{ if gt $img.Width 604 }}
{{ $small = $img.Resize "604x q95" }}
{{ else }}
{{ $small = $img }}
{{ end}}
{{ if gt $img.Width 800 }}
{{ $medium = $img.Resize "800x q95" }}
{{ else }}
{{ $medium = $img }}
{{ end}}
{{ range uniq (slice $medium $small $very_small $smallest) }}
{{ $src = $src | append (printf "%s %dw" .RelPermalink .Width) }}
{{ end }}
<img src="{{$medium.RelPermalink -}}" srcset="{{ delimit $src `, ` }}" loading="{{with .Attributes.loading}}{{ . }}{{else}}lazy{{end}}" {{with .Attributes.loading}}fetchpriority=high{{end}} {{with default .Title .Text }}alt="{{.}}"{{end}} {{ with .Title }}title="{{ .|plainify }}"{{end }} sizes="(max-width: 350px) 100vw, (max-width: 600px) {{if in .Attributes.class "center"}}100vw, 70vw{{else}}50vw, 400px{{end}}" {{with $medium}}width="{{.Width}}px" height="{{.Height}}px" style="--height-limit:{{.Height}}px; background: linear-gradient({{- delimit ($img.Colors) ", " -}})"{{end}}>
</a>
{{end}}
{{ if not .IsBlock}}{{ errorf "%q %q: Here images wrongly stacked on the same line" .Page.Path .Destination }}{{end}}
{{ end }}