Vinyasa layout: how to enable excerpts?

The Vinyasa demo site does not display blog post excerpts on the blog/archive page.

The source code on the demo site and my own site shows:

<div class="entry-summary" itemprop="text"></div>

Customize > Layout > Blog > Content type is set to excerpt.

I can't spot any css related to .entry-summary or a setting in an element that would be responsible for hiding it. But I may very well be overlooking it.

Does anyone know how to make excerpts show up using Vinsaya?

Thanks you very much in advance!