Upload Image for Facebook not working

I am trying to add an alternate image so that Facebook will show this alternate instead of the Featured Image that is associated with my post.

I go to the sharing settings at the bottom of the post and click on Upload Image but nothing happens. I tried entering the url manually and then clicking Upload Image — still nothing.

I am using the latest Yoast SEO and my website/post is here:
http://hansonfilm.org/conversation-diversity-opportunity-hollywood-film-tv-producer-moctesuma-esparza/

Thank you for a great plugin, hope this is an easy fix!

https://wordpress.org/plugins/wordpress-seo/