An event with a weak set of match keys is delivered, accepted and counted - and matched to nobody. The first half below estimates how far a given selection gets; the second normalises and hashes a single value the way Meta expects it, so a mismatch can be seen instead of guessed.
Which parameters does the event carry?
Normalise and hash a value
Meta prescribes an exact form per parameter. A value hashed in the wrong form produces a hash that is valid, accepted and matches nothing.