Brands shortcode image sizes

Hi. On our home page I have added the default shortcode listed on your github page: [pwb-all-brands per_page=”10″ image_size=”medium” hide_empty=”false” order_by=”name” order=”ASC” title_position=”before”]

2 of the 3 brand images display as 768×768.jpg but Avast displays as 768×400.jpg which knocks around the brand section as a whole.

How do I display Avast as a 768×768.jpg instead of a 768×400.jpg?

Thanks.

The page I need help with: [log in to see the link]