How an order dies quietly
The checkout succeeds, the retailer asks the bank to charge the card, and the bank pushes an approval to the phone that card belongs to. Most banks give you around five minutes. If that phone is in a drawer, on silent, or belongs to a family member whose card you're using, the approval expires and the retailer cancels the order. You won't always get an email about it.
Multiply that by the number of cards in play and a busy release, and it's easy to lose a third of your checkouts to approvals nobody saw.
The usual workarounds and why they break
People keep every banking app on one phone, which works until two banks push at the same moment and one gets buried. Others sit family members by their phones during a drop, which works exactly once. Some switch to cards without 3DS, which limits which cards you can use and doesn't help with the ones you already have.
What actually fixes it
Every approval request, from every card, in one feed, with the amount and the merchant, so you can see at a glance which ones are yours and hit them in time. Sorted newest first, with an alert the moment one arrives.
That's what Minted's 3DS alerts do for members. Approval prompts from your cards show up in one place, alongside your checkout notifications, so a drop with ten checkouts is ten taps in one screen instead of a scramble across three phones.