What to use when Analytics misses the commission
Google Analytics is the right tool when key events fire on a site or app you control.
People leave Analytics when a commission never shows up as a key event. The network approved it on a checkout Analytics does not host, and the property had no URL waiting for that call.
Compare ClickMagick and Google Analytics. ClickMagick documents server-to-server postbacks with affiliate networks, and it lists Audience Optimization on the first paid tier. If you need events rather than visitors, the next comparison is ClickMagick vs Voluum. Voluum's homepage presents the product as filling the measurement gaps buyers associate with Analytics.
Hosting the page and the checkout yourself is a different decision. The tracker or funnel platform picker helps you choose a dedicated tracker, a funnel platform, or both.