Twitter Thumbnail

I have a web page with its plugin
https://compartimas.com/14555/asi-se-veia-la-bruja-del-71-de-joven/
Upload this image in imgur.com, to use it as thumbnail of my post

View post on imgur.com

and it does not work on twitter
https://cards-dev.twitter.com/validator

Do you know why it can be?

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