Pixel not firing. Open the Network tab and filter for financeads.net/tl.php. No request means the trigger is off; confirm the tag fires in GTM Preview.
Conversions missing from the dashboard. Confirm the Program ID matches your advertiser account. A wrong ID means the pixel fires but FinanceAds cannot attribute it.
Wrong conversion category. Check the dropdown. Using lead where you meant sale misclassifies the conversion in reporting.
Duplicate conversions. A reloaded confirmation page fires the pixel again with the same order ID. FinanceAds may deduplicate on their side, but firing once per order is better practice. Use a dataLayer flag or a first-party cookie.
Sub ID not tracked. The field is optional; left empty, the s_id parameter is omitted. If you do want it, make sure the variable resolves to a string.
Ad blocker interference. The financeads.net domain can be blocked, and since this is a plain image pixel there is no JavaScript fallback. Server-side GTM helps if the loss is significant.