I bought some gift cards for our previous trip - probably just over $1000 all together. I never checked if they were activated after purchasing them at Target- just that they were all listed on the receipt. Upon check in I had the front desk add them to my magic band. One card was coming through as having $0 on it. I couldn't believe it. I had the CM check it multiple times. I checked it on the Disney Giftcard site from our room and it said it had never been activated.
When I returned home, luckily I found the receipt with the card number on it, otherwise there would have been nothing they could do. As it was, Target refused to do anything. Disney worked it out after a number of phone calls and emails back and forth. So lesson learned... Check those cards as soon as you buy them!