@prabhjot hey, thanks for a great question, and I hope Stamos and myself will be able to solve your issue.
So besides what Stamos said, which is a great point, there are also two things you want to look at, and both have been addressed in previous Community posts.
THIS POST discusses the matter of whether Shopify actually sends the correct data into Klaviyo, which would explain why, even if your syntax is correct, you’d still get this error message - the data are missing and thus your final render is empty.
Further to that, THIS POST this post discusses using the correct trigger in your flows which will ensure the correct data is pulled into the syntax. E.g. if you’ve created your flow using a checkout started trigger, and then tried creating order confirmation emails within that flow, you’d get a lot of syntax errors as the data pulled from the trigger are incompatible (and vice versa, of course).
Happy to chat further!