The reason that nothing is showing up is entirely because your site is restricted to members only. In order for you to share items on Facebook and still have these info appear, your items need to be public.

Please refer to Facebooks guide here for more details, https://developers.facebook.com/docs/sharing/best-practices#crawl

I'm confused then as yes the ES part of the site is members only but I can post from Groups? I can set Group Modules as public and it seems to be ok but Events do not...what am I missing?

In short, if you cannot access the page as a non logged in user, then that link wouldn't work on Facebook. I believe you have one of your menu item referencing to events and it is set to "Registered".

I understand in principle but I can see the Event (not logged in) and the Menu Item (see attached) is public

If you have just made it public, you need to tell Facebook to purge it's crawler's cache. To do so,

1. Go to https://developers.facebook.com/tools/debug/sharing/ . Enter your url that you are trying to share

2. Click on the debug button, http://take.ms/2qk9O

3. Then click on the "Scrape Again"

so then in FB scrape cycle all events will be included?

It only refreshes the cache of that url that you are trying to clear. For other urls that wasn't scraped before, it wouldn't be cached.

This unfortunately is not something that we can control.

Thank you for your help.

No problem.