Include content of a block in a view template
You can't mix different templates types like views and block templates. Every template has other variables and so the block template doesn't find the content variable in the views template context.

In your case for a View you could place the block in the header or footer in Views UI. For example a Rendered entity - Block.

In general you can use the module Twig Tweak instead of {% include %} to render a block template or any other entity template:

{{ drupal_entity('block_content', 1) }}


This works, because it renders the entity in its own variable scope and so you can place it everywhere in twig.



While entities normally render in their own template, block content is special, because it doesn't have a template on its own. So the command above only shows the fields. To get the block wrapper you need to use drupal_block().