You need to use the handle of the blog: `https://yourstore.com/blogs/this-is-the-handle`. It should be lowercase.
The other thing to check is if there’s a global `product` object. If you’re on a product page, there will be, but if you’re testing it on another page there might not be.
The code snippet I sent is also missing the last part. There’s no user-creatable array type in Liquid, so the indices are stores in a hyphen separated string. So, `articles` needs to be split on hyphens, and then coerced from a string to a number by adding a `| plus: 0` filter before using it to index `blog.articles`. Like this:
{%- assign blog = blogs['press'] -%}
{%- # double-check that `press` is the right handle by checking the URL of the page that lists all the blog posts -%}
{%- assign limit = 3 -%}
{% liquid
assign articles_to_display = 0
assign articles = ''
assign index = 0
for _ in (1..50)
for _ in (1..50)
if blog.articles[index] and articles_to_display < limit
for related_product_ref in blog.articles[index].metafields.custom.press_products
if related_product_ref.id == product.id
assign articles = articles | append: '-' | append: index
assign articles_to_display = articles_to_display | plus: 1
break
endif
endfor
assign index = index | plus: 1
else
break
endif
endfor
unless blog.articles[index] and articles_to_display < limit
break
endunless
endfor
assign articles = articles | remove_first: '-'
assign article_indices = articles | split: '-'
%}
{% if article_indices.size == 0 %}
<p>Goodnight</p>
{% else %}
{% for article_index_str in article_indices %}
{%- assign article_index = article_index_str | plus: 0 -%}
<h2><a href="{{ blog.articles[article_index].url }}">{{ blog.articles[article_index].title }}</a></h2>
{% endfor %}
{% endif %}
