block.super doesn't work with pages

Using cryogen-core 0.3.1, I'd like to create a new page that overrides the default template's content block, inserting the original via {{ block.super }} (info in Selmer README). Instead I get the page template rendered with no values populated.

The project was freshly created using the default page.html template. I added a page-premium.html template with an extends block:

{% extends "/html/page.html" %}

{% block content %}

  a
  {{ block.super }}
  b
  
{% endblock %}

And the page premium.md:

{:title "Premium"
 :layout :page-premium}

Premo.

What I see is this:

And I'd expect to see "Premo." on the page between a and b.

Does it still not work with latest Cryogen and its updated Selmer?