None of this makes sense. I realize you said you didn’t know the exact amount … anything $1200 and above generates a hand pay and a tax slip is issued. The win is paid out via cash in hand or a slip you take to the cage to redeem. If she truly hit a jackpot … The only way the money could still be in the machine when she left would be because she deposited the money into the machine after she received her money. I further understand that the jackpot she hit could have been a large amount.. but not enough to lock up the machine. Also, whenever you pull your card and leave the machine, the credits automatically deposit into your “casino bank” on your card … even if you don’t hit the cash out button. I don’t see that it’s possible for the credits to stay on the machine after the card was pulled. Please don’t misunderstand me, I realize the information you’ve relayed is based solely on what you read on FB. Not blaming you at all. Just a very confusing tale.
edit … after rereading your post I see that the credits didn’t automatically transfer on three different occasions while you were playing. This is a problem that Carnival needs to address.