What merchants usually notice
Typical signs include purchases appearing in Shopify but not in the advertising platform, the same order appearing more than once, or reported revenue drifting far away from actual store revenue.
Check the customer journey first
Start with the events that matter to the business, such as product view, add to cart, checkout and purchase. Shopify exposes standard customer events, including checkout_completed for a completed purchase, so the first job is to identify which step is missing or inconsistent.
Compare browser and server-side tracking
Shopify supports browser-based web pixels and, for certain app owners, server pixels. If both paths are in use, review how the destination receives each signal and make sure one purchase is not accidentally reported twice.
Check privacy and consent behavior
Tracking is still subject to customer privacy and consent settings. Test the setup in the regions and consent states that matter to the store instead of assuming every visitor produces the same signals.
Verify with a real test order
Complete a controlled order and compare the order in Shopify with the events received by the connected analytics or advertising service. The goal is to confirm that the completed purchase is represented consistently, not simply that some tracking request was sent.
Monitor after the fix
Compare actual Shopify orders with reported conversions over several days. Small timing differences can happen, but large or persistent gaps deserve another review.