So I found a local grocery store near me who has no problem letting me use my MCGC debit for money order purchases. I noticed that I can only swipe two that are approved and then a third swipe causes an invalid transaction. Even if I do 3 separate money orders I still get the invalid transaction on that 3rd money order. So I just ended up leaving and coming back the next day to purchase 2. Did this every day until I used all my MCGCs.