Twitter Thumbnail is not showing up

The featured image used has shown up on Facebook when posting but has never displayed on Twitter though now it won’t show up on either. I have tried to post each article individually but the image never shows up for both Facebook and Twitter. I am trying to schedule posts for certain times not just as soon as they are published on the site but none of the images appears on the social media sites.

• This topic was modified 4 years, 3 months ago by bellaturolla.
• This topic was modified 4 years, 3 months ago by bellaturolla.

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