Facebook preview caching old/offline version, wrong image displayed

Facebook picks random images from your page, depending on pixel sizes and other rules, unless you specify one specifically. 

If facebook shows the wrong image or text for your shared web page, then this is how to fix it. 

1. Login to our CMS
2. Hover over your home page (or other relevant page)
3. Click the COG icon. 
4. Scroll down to "Social Share Image"
5. Browse for an image to be your primary shared image. It needs to conform to some facebook standards, or facebook may ignore your choice.
6. Publish
7. Wait about 5 minutes for publishing to continue around the globe.
8. Now go to Facebook Debugger
9. https://developers.facebook.com/tools/debug/
10. Enter your live page URL, DEBUG
11. You may see an error message like "The 'og:image' property should be explicitly provided, even if a value can be inferred from other tags.", that is what you have just fixed.
12. Press SCRAPE AGAIN button
13. you should now see the correct image... 
14. if not, double check your image is good for Facebook rules, then wait a minute, and try again. 
15. If continued errors, try a different image...