Missing image preview in tweets

Recently we’ve been finding intermittently the preview of articles tweeted by WP to Twitter will have nothing but a blank white box where the image preview usually goes.

see: https://www.create.ac.uk/wp-content/uploads/2019/03/Screenshot-2019-03-19-at-14.18.47.png

It doesn’t seem to matter if the posts contain images or have featured image set, or not.

Is anyone else having this problem, and does anyone know of a fix/workaround for this?

Thanks

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