I found the problem. There is an extension on the our Magento Instalation called amasty color swatches which has a script on the page which disables the additional info tab.
here it is:
<script type="text/javascript">
var amConfAutoSelectAttribute = 1;
confData = new AmConfigurableData({"9":{"short_description":"<p>Lorem Ipsim<\/p>","description":"<p>More Lorem Ipsum<\/p>","not_is_in_stock":false,"attributes":" <h2>Additional Information<\/h2>\n <table class=\"data-table\" id=\"product-attribute-specs-table\">\n <col width=\"25%\" \/>\n <col \/>\n <tbody>\n <tr>\n <th class=\"label\">TEST ATTR<\/th>\n <td class=\"data\"><p>More Lorem Ipsum.<\/p><\/td>\n <\/tr>\n <\/tbody>\n <\/table>\n <script type=\"text\/javascript\">decorateTable('product-attribute-specs-table')<\/script>\n","name":"COnf Atr 1","price_html":"\n\n // code ommited for brevity
confData.textNotAvailable = "Choose previous option please...";
confData.mediaUrlMain = "http://dev.domain.local/amconf/media/index/id/13/";
confData.oneAttributeReload = "1";
confData.imageContainer = ".product-img-box";
confData.useSimplePrice = "1";
</script>
I was unable to disable this setting from the extensions settings on the admin panel. I had to comment out line 62 of
app/code/local/Amasty/Conf/Block/Catalog/Product/View/Type/Configurable.php
//'attributes' => Mage::app()->getLayout()->createBlock('catalog/product_view_attributes', 'product.attributes', array('template' => "catalog/product/view/attributes.phtml"))->setProduct($simple)->toHtml()
I don't think this is a good solution though as the extension is grabing this data to swap simple product attributes with the parent configurable product attributes on the product view page. I think the whole issue arises as the module is not compatible with Magento 1.9 rwd theme which puts the additional information in a tab.