Programatically Sending Transactional Emails Doesn't Include Products

Question

When I send out my transactional email programatically, I'm not getting any items in a table like I do when the email is sent automatically.

Looking into the templates, the information is pulled across via:

{{layout handle="sales_email_order_items" order=$order}}

This is sending directive:

$emailTemplate = Mage::getModel('core/email_template')->loadByCode("More Information Required");
$emailTemplate->setSenderEmail(Mage::getStoreConfig('trans_email/ident_general/email', Mage::app()->getStore()->getStoreId()));
$emailTemplate->setSenderName(Mage::getStoreConfig('trans_email/ident_general/name', Mage::app()->getStore()->getStoreId()));
$emailTemplate->send($order->getCustomerEmail(), $order->getCustomerName(), [
    'order' => $order,
    'customer' => $order->getCustomerName(),
    'dateAndTime' => $order->getCreatedAt()
]);

All the data is filled correctly, except the order items grid. Nothing is displayed for this.

Update
To answer the question in the comments, the $order variable is generated as a result of an observer action on an event (in this case, sales_order_save_after). The variable that eventually becomes $order (when passed into a function) is formed as follows:

$observer->getEvent()->getData('data_object')

This contains a standard order object, of the following class: Mage_Sales_Model_Order

Answer 1

I'll take a shot in the dark.
If you send e-mails from an "area agnostic" script then the layout directive does not know from where to load the handle sales_email_order_items.
Take a look at the layoutDirective method from the Mage_Core_Model_Email_Template_Filter class. This is the class that parses and interprets the email templates:

    if (isset($params['area'])) {
        $layout->setArea($params['area']);
    }
    else {
        $layout->setArea(Mage::app()->getLayout()->getArea());
    }

In your case $params['area'] is not set and you fall on the else case.
but here Mage::app()->getLayout()->getArea() most probably has no value.

You can try to change this

{{layout handle="sales_email_order_items" order=$order}}

to this

{{layout handle="sales_email_order_items" order=$order area="frontend"}}

or

{{layout handle="sales_email_order_items" order=$order area="adminhtml"}}

to see what happens.