It's one of the most common tracking problems I'm hired to fix: the tracker counts every click, the ads are spending, and the revenue column stays at zero. The good news is that it almost always comes down to one of a few causes.
1. The click ID never reaches the checkout
Your tracker attributes a sale by matching it to a click ID. If that ID is lost between the ad and the checkout, the sale can't be matched to anything. This happens when a lander's buttons don't pass the click ID on, when a funnel moves to another domain, or when a quiz platform drops URL parameters between steps. The fix is to check every hop, from ad to lander to checkout, and confirm the click ID is still there at each one.
2. The checkout platform doesn't send it back
Many hosted checkouts and intake platforms send webhooks when an order happens, but don't include the click ID. Your server receives the sale, but has no way to tell the tracker which click it belongs to. On one telehealth build, the platform's webhooks carried no click ID at all. The fix was to capture the click ID in the browser and send each funnel event through the platform's own script hooks, plus a server-side purchase event from Stripe.
3. The conversion type doesn't match
If your postback sends a conversion type with a typo, some trackers won't reject it. RedTrack, for example, records it as a generic conversion, so the sale shows up in the wrong place, or not where your reports look. Always check new conversion types in your reports before launch.
4. The purchase fires from the wrong place
Purchases sent from the browser can be blocked or missed. Purchases sent from the server, triggered by the payment itself, are far more reliable. Where you can, send the purchase server-side and make sure it only fires once per order.
How to check your own setup
Run one real test: click your own ad or tracking link, go through the funnel, buy, and then look for that exact click ID in your tracker's conversion log. If the click is there but the conversion isn't, the problem is between your checkout and your tracker. If the click ID changed along the way, the problem is in your funnel.