Webflow → Shopify checkout tracking gaps (GA4 + Meta Pixel + Conversions API)

Hi everyone

I’m dealing with tracking and attribution issues in a Webflow front-end → Shopify checkout setup and would really appreciate insights from anyone who has implemented this reliably.

Setup

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  Webflow landing pages (custom storefront, non-Shopify theme)

  
  


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  Users are redirected to Shopify checkout on a different domain

  
  


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  Traffic primarily from Meta Ads

  
  


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  Tracking stack:

  
  
  
  
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    Meta Pixel (browser)

    
    
  
  
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    Meta Conversions API (server-side)

    
    
  
  
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    GA4

    
    
  
  
  
  

Problem

We are seeing missing and inconsistent ecommerce events, especially over time:

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  AddToCart, InitiateCheckout, and Purchase sometimes don’t fire

  
  


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  Meta attribution quality degrades (CPM increases, fewer attributed conversions)

  
  


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  GA4 purchase counts do not consistently match Shopify

  
  


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  fbclid / fbp / fbc sometimes only appear on InitiateCheckout, not earlier events

  
  


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  Some sessions seem to disappear when users are redirected to Shopify

  
  

GA4 pageviews on Webflow fire correctly, but Webflow Add to Cart isn’t always firing and Shopify does not always create a session or attribute the user properly after redirect, even though Conversions API is enabled.

Does anyone know how to set up this properly?