Reports in the comments at Doctor of Credit indicate that Mastercard gift cards can no longer be used as debit cards at Walmart stores. Only being able to run these gift cards as credit limits their scope of functionality.
Getting a Mastercard gift card to process as debit at Walmart has long required a bit of song and dance and quick mashing of buttons to my understanding, so I haven’t personally bothered with them at Walmart in a long time. However, I know that with office supply stores occasionally running fee-free deals on Mastercards, there are many people who may hope to be able to use them at Walmart as debit. Unfortunately, it looks like that will no longer work with the payment terminals reportedly saying “Tender not allowed” without the opportunity to run as debit. To be clear, this likely only affects transactions which ordinarily require a debit card like loading Bluebird/Serve and buying money orders. Unfortunately, it looks like this applies at all payment terminals.
This is an unfortunate change for those who were using Walmart to liquidate these cards.