How to Regenerate Thumbnails
After installing the Genesis Framework and your child theme, we highly recommend regenerating the thumbnails for any existing images on your site. This will ensure that all image sizes that are defined in the theme are available in your site as you work to configure all the settings described in this theme setup guide.
To do this, we recommend using the Regenerate Thumbnails plugin.
After you’ve installed and activated the Regenerate Thumbnails plugin, go to Tools > Regen. Thumbnails.
Then click the Regenerate All Thumbnails button to begin regenerating the thumbnails on your site.