Datapoint, maybe tl;dr, based on experience today at Giant in No. Virginia --
Purchased 3 metabank Visa GCs, $500 each, paid with single CC. Sale completes, clerk gives me receipts & activation slips. On the way out the door, I noticed I only 2 of the little activation slips, then noticed that one of the GCs listed on the store receipt said "Not Approved."
Went back inside, thankfully the CSR was on the ball and could easily see that I was effectively charged $500 for a seemingly worthless GC. He went back to rack, got another GC of same type, and I walked away with the new card & activation slip.
Still not exactly sure what happened, or would have happened, if I didn't exchange the card, but it's a lesson to me to double check the receipts on future GC purchases.