Magento – Magento 2 – Get custom attribute within .phtml file using Magento\Catalog\Block\Navigation class

I am trying to get a custom attribute value within my phtml file but struggling to get this to work? getData() & getCustomAttribute() doesn't seem to work. I believe this is because I am using the Magento\Catalog\Block\Navigation class to loop through my categories?

Can anyone advise how I can get my custom attribute value within my loop in my product-categories.phtml?

default.xml within my theme

<block class="Magento\Catalog\Block\Navigation" name="product.categories" template="Magento_Theme::html/product-categories.phtml"></block>

product-categories.phtml

<?php
if (!$block->getCategory()) {
    return;
}
$_categories = $block->getCategory()->getChildrenCategories();
$_count = is_array($_categories) ? count($_categories) : $_categories->count();
if ($_count) {
    ?>
    <ul class="list-quicklinks row med-gutter">
        <?php 
        foreach ($_categories as $_category) {
            if ($_category->getIsActive()) {
                ?>
                <li>
                    <a href="<?php /* @escapeNotVerified */ echo $block->getCategoryUrl($_category) ?>" title="<?php echo $block->escapeHtml($_category->getName()) ?>"><?php echo $block->escapeHtml($_category->getName()) ?></a>
                    <?php
                    //$short_description = $_category->getData('short_category_description');
                    //$short_description = $_category->getCustomAttribute('short_category_description');
                    //$short_description = $this->helper('Magento\Catalog\Helper\Output')->categoryAttribute($_category, '', 'short_category_description');
                    ?>
                    <p><?php // echo $short_description; ?></p> 
                </li>
                <?php 
            }
        }
        ?>
    </ul>
    <?php
}
?>

UPDATE:

namespace Autosmart\CategoryAttributes\Model;

class Category extends \Magento\Catalog\Model\Category
{
    public function getShortCategoryDescription()
    {            
        //return "working";  
        return $this->_getAttribute('category_short_description');
    }
}

I've created a modal with custom function getShortCategoryDescription() which I can call by $_category->getShortCategoryDescription() however I am unsure how to get this to return my short description attribute. The above code gives me an error:

1 exception(s):
Exception #0 (Magento\Framework\Exception\LocalizedException): Invalid method Module\CategoryAttributes\Model\Category\Interceptor::_getAttribute