Hi Robert,
I just removed the code default by Helix3 framework. By default, the article will show up intro text from joomla article as meta description, so if you wish to use your custom meta description, simply remove the code like this
$document->addCustomTag('<meta property="og:description" content="'. JHtml::_('string.truncate', $this->item->introtext, 155, false, false ) .'" />');
template folder -> html -> article -> default.php line 42
NOTE: I just commented the code above for default.php file
Now facebook will fetch the content from your meta description of article instead the joomla intro text.
Please clear caches for joomla then recheck.
