You need to change your way to get product attributes in phtml:
you can get attributes using <?php $attributes =  $block->getAttr($_item->getProductId());   ?>
and after that you need to change function defined in block as:

public function getAttr($id)
{

        $product = $this->productFactory->create()->load($id);
        return $product;
}

Now you can get all attributes in below way:
<p>echo $attributes->getName();<p>
<p>echo $attributes->getPrice();</p>
In this way you can get any other custom attribute's value.

Hope this was helpful.