The click id vanishes somewhere in the chain: what to check
Ad platforms have a specific alert for this, and its entire remedy is to have someone spot what is wrong on your side. That is the complete instruction, and it bypasses the only question you really have: which hop of the chain loses the marker. The path answers that itself, aloud, if you ask it with one request instead of a browser tab. The checks below take about a minute together and they run in any order.
What to consider
- Run the same request against an address you already know is sound before trusting the result on the suspect one. A sound chain carries the marker through every hop and ends on a plain success, and seeing that once makes a faulty chain obvious.
- Regard the first exposed target as the culprit and stop there. A parameter that is missing cannot return, so every hop after that one is innocent no matter how it appears.
- Check the status codes as well as the targets. Some codes retain the method of the request and others may not, so a click that arrives as a form submission can drop data in a way that has nothing to do with the query string.
- On a mass list, the setting that carries the incoming query string through is off unless somebody turned it on, and that is the most probable cause of the warning on a zone of this kind.
A browser is the wrong instrument for this particular question. It shows the address you landed on and hides the path that produced it, and it executes the page’s own scripts, which can restore a parameter and make a broken chain appear healthy. Anything that speaks plainly and follows the hops for you will do.
Where the leak is not a hop at all
Parameters also disappear in places that never appear in a trace: a link altered by a mail client before it is sent, an in-app browser that strips the address before the request goes out, a script that replaces the address after the page has loaded. None of those leave a hop to look at. If the trace is clean and the numbers are still missing, that is where to go next, and it is worth knowing before an afternoon disappears into rules that were fine all along.
The identical test written out, with a tidy route next to a damaged one: affiliate conversion tracking
Read from the top and halt at the first line that lost the marker. One call names the hop, and the fix belongs to whoever owns that hop, which is typically a configuration rather than an outage.