When inside front matter you specified series with spaces,
then the opengraph template wouldn't detect other articles,
because in `.Site.Taxonomies.series` they are stored by
urlized key.
Example:
```yaml
# in front matter
series:
- My Series
```
```gohtml
{{/* in a template */}}
{{- $series := index .Site.Taxonomies.series$name }}
{{/* was resolved to */}}
{{- $series := index {'my-series': ...} "MySeries" }}
```
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