If test results cannot be reproduced, start by preserving one representative example. It gives the investigation a concrete reference and makes the eventual correction easier to judge.
Find the likely cause
The team failed to record the tested versions.
Treat this as an explanation to verify against the actual work. Look at the input, the relevant decision, and the final result together. If the evidence does not support this diagnosis, investigate the mismatch before applying a convenient but unrelated fix.
Make the targeted correction
Save exact copy, audience rules, dates, and destination pages.
Message testing should isolate the idea being tested so a result can inform the next decision.
Check that the repair worked
Another person should be able to reconstruct the test from the record.
Repeat the check on the final version that the reader or customer will encounter. An approved draft, a preview, and a published result can differ; the acceptance decision should concern the version people actually use.
Prevent the next related failure
A separate issue to watch for is this: message tests change too many things at once. Keep the offer and delivery conditions stable while changing one message dimension.
Monitor the useful outcome
Use qualified responses per eligible exposure and record sample size, traffic source, and test duration.
Keep a short record of the original symptom, the evidence behind the diagnosis, and the result of the acceptance check. That record makes the solution reusable when the same condition appears again, without assuming that every superficially similar problem has the same cause.