Error with assets deferred

Hi.

When I try to defer assets with assets.addLink in a stylesheets block, I get the following error:

An exception has been thrown during the rendering of a template ("Property 'link_pipeline_include_externals' does not exist in the object!")

I have a block with:

{% block assets deferred %}
    {{ assets.all()|raw }}
{% endblock %}

And in {% block stylesheets %} an entry with {% do assets.addLink('https://fonts.googleapis.com/css?family=Lora:400,400i,700', {rel:'stylesheet'}) %}

What am I doing wrong?
Thanks.

Tnaks @b.da

I read in the Grav help that addLink "It is useful for adding link tags to the head from anywhere in your site that are not CSS files"