notify Me button not showing after installed code snippet in Bigcommerce

I added the snippet to the script manager in bigcommerce, but the notify me button isn’t appearing on out of stock products.  I have compared the code side by side with the Klaviyo article and it is identical.  How can I get this working?

Code is pasted below, with the exception of the Public API Key and list ID, which I have removed for security purposes.

<script src="https://a.klaviyo.com/media/js/onsite/onsite.js"></script>

<script>

     var klaviyo = klaviyo || [];    

     klaviyo.init({  

          account: 'PUBLIC_API_KEY',

          list: 'LIST_ID',

          platform: 'bigcommerce' 

     }); 

     klaviyo.enable("backinstock",{   

     trigger: { 

          product_page_text: "Notify Me When Available",

          product_page_class: "button", 

          product_page_text_align: "center",

          product_page_margin: "0px",

          replace_anchor: false

     }, 

     modal: {  

          headline: "{product_name}",  

          body_content: "Register to receive a notification when this item comes back in stock.",  

          newsletter_subscribe_label: "Add me to your email list."

button_label: "Notify me when available",

email_field_label: "Email",  

          subscribe_checked: true

          subscription_success_label: "You're in! We'll let you know when it's back.",  

          footer_content: '',  

          additional_styles: "@import url('https://fonts.googleapis.com/css?family=Helvetica+Neue');",  

          drop_background_color: "#000",  

          background_color: "#fff",  

          text_color: "#222",   

          button_text_color: "#fff",  

          button_background_color: "#4787ed",  

          close_button_color: "#ccc",  

          error_background_color: "#fcd6d7",  

          error_text_color: "#C72E2F",  

          success_background_color: "#d3efcd",  

          success_text_color: "#1B9500" 

          }

     });

</script>