Holding ALT and clicking on a pin should display it on the minimap, and if its offscreen it should rotate with your orientation so you know which direction to go.

But that's literally how it works already

Are you clicking on the pins on the left hand side of the atlas?

Mate, I'm literally using the Atlas right now and it doesn't do that. The pins only show up if you're in the map that contains them.

No, that just makes the map move over to them. There's no option to make pins appear on the minimap wherever you are.