Well, I know it doesn't help much, but for what it's worth: when a card isn't in right but is able to autoconfigure, you'll know about it! The Amiga will boot into the Early Startup Menu, but instead of grey it'll be red. It'll also describe the dodgy card as "Faulty" instead of "Working".
I presume you have tried cleaning the contacts? Tried a different Zorro II board in the machine? Tried the board in a different machine? Otherwise check all the chips are seated properly.
