Star rating is a dropdown box instead of stars per documentation

Hi I have just deployed this plugin and everything is working, however, when I create a review page with the shortcode [woocommerce_photo_reviews_form] the form displays OK but the “Your Rating” is displayed as a dropdown with a choice of words instead of choosing a star rating. This looks different to the documentation which shows the option to choose a star rating. How do I make it work this way?