Thumbnail Image is not generated on Listing Page

I am using latest version of DirectoryPress Responsive Theme v6.0

On Listing page my post is not showing thumbnail image of the post, instead of it, it’s showing full size image.

Listing Page : https://www.gicn.in/new/person/aditya-agarwal/

Image URL : https://www.gicn.in/new/wp-content/uploads/aditya-agrawal.jpeg

I am not getting any option to select image size while selecting “Featured Image”. However when I add images from “Add Media” button under Item Description tab, I am getting size selection option, but this does not work as images are added as a part of description.

I think this is because Premiumpress is using Custom Post Type. I found some discussion on WordPress site (https://wordpress.org/support/topic/media-library-attachment-display-settings-in-a-custom-post-type) but not sure why it’s not showing up in Directorypress?