Some basic things to check if you're having issues

One common issue is that your website is outputting duplicate sets of the same open graph tags (usually because your theme or another plugin is already doing it).

While Facebook will still be able to scrape your page, it could be using the ‘wrong’ set of open graph tags.

A quick test is to simply view the source code of the page and search for…

og:

…and see if you’re getting any duplicate open graph tags.

For this plugin, you should see something similar to this output when you view the source of your page (but with details of your own website of course):

<!--/ Facebook Thumb Fixer Open Graph /-->
<meta property="og:type" content="product" />
<meta property="og:url" content="https://taskrocket.info" />
<meta property="og:title" content="Task Rocket" />
<meta property="og:description" content="Task Rocket is the awesomest front-end project management theme built on WordPress." />
<meta property="og:site_name" content="Task Rocket" />
<meta property="og:image" content="https://taskrocket.info/wp-content/uploads/2016/03/facebook.png" />

But if you find any more than one instance of any of the same open graph tag – og:title for example – then one of two things might be the case:

1) Your theme may already output open graph tags (in which case there’s no need for a plugin).
or
2) You’ve got more than one plugin that outputs open graph tags.

You’ll need to work out for yourself what the case is through a process of elimination, by switching to a default theme and or disabling plugins until you only have one set of outputs open graph tags being output. Then go from there.

Good luck.

https://wordpress.org/plugins/facebook-thumb-fixer/