Cannot reference custom profile properties in email template

Hi there, 

I’m trying to replicate this article to insert recommended product IDs into profile properties and referencing them in email templates: https://help.klaviyo.com/hc/en-us/articles/360004785571-The-Catalog-Lookup-Feature

I’ve successfully created a custom property on the profile I’m targeting, and am inserting the code block into the text block of the email template editor, however upon previewing the email, I can see the for loop skipped which renders a blank text block. 

Under profile property section when previewing the email, I also cannot see my custom property in the list. Am I doing something wrong? Can someone help?