Hi all,
As snake eye has said, a setup zone hasn't an influence on the mines. At the beginning of the scenario (Setup Phase) they'll always exactly appear were you had placed them when building the scenario, and if they are inside a setup zone the Red player (never the AI) can choose to relocate them within all the limits of the setup zone, as you could do with any kind of troops/vehicles inside the setup zone. But this isn't the case here.
jkobmadrid, you might have assigned some of your mines to an AI Group. In the Unit Editor's "Purchase Units" option, take out all the [A2]-[A8]s to the right of the mines name. They all should have to be in the general Group 1, to avoid mixing them with any of your AI plans, so highlight them and press F1. At the Setup Phase the mines assigned to an AI Group will automatically move to the Map Zone for the Setup Order of their Group, that it has to be painted inside a valid Red Setup Zone. Please go to the AI Editor and see that you have painted a Map Zone for a Setup Order of a Group (Group 1 if your mines weren't assigned to any AI Group: [A2]-[A8]). That's in yellow color over the reddish background of the setup zone. The AI is automatically moving those mines there at the beginning of the scenario. Don't paint a Map Zone (yellow) for a Setup Order of Group 1. Use this Group for all the stationary units.
Cheers,
Lomir