Dell CS Claims Regular Gift Card Expired

I have a Dell gift card (a regular one and not a promotional card) that has a $25 balance. My issue began when I used this card to make a purchase. During checkout, Dell tells me the card has a $25 balance (see photo attachment). When I complete checkout, I get an email from Dell saying, "We’ve encountered a payment issue," and that it's unable to process payment. I've spoken to six different representatives, spent over three hours on the phone trying to resolve this, and have been transferred between multiple departments. The last answer I received was that the gift card expired, but written on the back of the card, it explicitly states "Available funds do not expire." When I asked to speak to a manager about this, I was put on hold for half an hour and then hung up on.

Can a competent representative please assist me with this? Thank you.