There has been some discussion of this issue in the FT-MS thread for Kroger, which is where it happened to me using MCGCs issued by Meta/Blackhawk. Also happened to me using same cards at Publix. Common denominator for me was using $500 cards for "full" $500 purchase, e.g., using it as first or second card in a 4-swipe $2k purchase at Kroger.
Since I need to liquidate other MCGC cards while this issue is being worked, I have adopted practice of using less than the full load on the card, e.g., buying a $498 MO with one swipe of a $500 card. I also filed Cardholder Dispute Form for each of my 3 cards that were drained.