A couple of examples:

index.php?option=com_content&id=63&view=article&Itemid=68 -> benefits-to-schools
index.php?option=com_content&id=58&view=article&Itemid=63 -> existing-schools
index.php?option=com_content&id=65&view=article&Itemid=70 -> news

The URLs look all right. Does it work with SEF completely disabled? (disable Search Engine Friendly URLs in Joomla's global configuration) Does it work with only standard Joomla's SEF enabled? (Search Engine Friendly URLs in Joomla's global configuration enabled, but JoomSEF disabled in JoomSEF's configuration)

Best regards,
ARTIO Support Team

It works with it completely disabled (Unfriendly URL's), Doesn't work with standard SEF though; seems to exhibit the same behaviour?

I'm sorry, but in that case it's not the JoomSEF problem, so I can't help you with that. Your .htaccess file looks all right and the SEF URLs are processed, because there's no 404 error when accessing them, so there is probably some problem with further processing of variables returned from SEF component in Joomla.
If you would like us to find the problem directly on your website, please, purchase 1 hour of our support time at www.artio.net/e-shop/support-services and contact us with the access information to your Joomla's administration and FTP.

Best regards,
ARTIO Support Team