Disabling PDO::ATTR_EMULATE_PREPARES causing 'unknown' issue

This looks to be a bug in certain PHP versions:

https://bugs.php.net/bug.php?id=61411

It seems there is a problem running both

PDO::ATTR_PERSISTENT => true

and

PDO::ATTR_EMULATE_PREPARES => true

Which you have in your PDO attributes/options array.