What's this 'online at a taco store' you're referring to? Is there a different method of getting them?
GamePlanet. It's a mexican store similar to Gamestop, but gives the codes online (with a limit of codes). They've started giving these codes since the last Shiny Gengar event. On both the Gengar and Diancie ones, they've been heavily abused by "Hola" extension (I was one of them, being a South American is suffering :V), a lot of actual mexicans whined about not getting codes and now they're taking action to limit the range of it. Heard they managed to block Hola, but I won't know until the next event.
Welp, went to gamestop and picked up 3 cards. All of them are A4AZ.
If you care about the IVs you could wait until the issue is resolved. It's most certainly server-sided.