Image or header not displaying for 3rd party

Hi
I’m concerned that this will happen to other new Enfold Theme websites we do.

When you copy and paste the URL from a Page or Post into say Facebook ‘What’s on your mind’ It doesn’t display the image, just a grey figure, and the text. With other themes, the main image is pulled in as well as the title and description.

3 examples in Google Drive folder from https://FindNetSolutions.com
One has a ‘Full-Width Easy Slider’ as the main top image. another the ‘Color Section’ and the other is an ‘Easy Slider’

Have you seen this and do you know what causes it?
My concern is if the image can’t be pulled into 3rd party sites, can Google index, or what other limitations do we have?

Here are 3 screenshots: https://drive.google.com/drive/folders/1A4ApBkP6QRtwZpcf965bZIs758GeVTxJ?usp=sharing

Thanks for your help :)

Cheers Dave