Portfolio main page isn't cropping images

Hi! I’ve been using the full width 2 column portfolio page. The thumbnails were the right size — the same as in the demo — but now they’ve become full size squares, the same dimensions as the featured images. I’m not sure how to set it back to the way it was. I haven’t altered the images.

You do have access to the site. It’s the ‘Featured Poets’ page here:

Thank you for helping!