I cannot work out why three different blog posts yield three different "share images" (i.e. when sharing the blog on social media or Slack etc), when all the JSONLD schema set up is the same, which you'll see if you run them through Google's Structured Data Testing Tool.
All of our blog posts are rendering a different or no image, so I picked three to give a breadth of scope.
1) Yields no image at all when sharing: https://search.google.com/structured-data/testing-tool/u/0/#url=https%3A%2F%2Fmyscoot.co.uk%2Fblogs%...
2) Yields the "logo" image when sharing (not the featured image) -
Hey @MyScoot. You've confused markup.
Facebook uses Open Graph properties. I suggest you use their Sharing Debugger tool to see the exact properties each page is using.
Have you recently changed the website? My tests show it is good. I can see your first page should be yielding an image when sharing:
Your second one: