The problem, having worked in banking, is that the core system is separate from the loans system, almost certainly. More complexity. Probably some semi-automate

The problem, having worked in banking, is that the core system is separate from the loans system, almost certainly. More complexity. Probably some semi-automated batch handling which is far more brittle and janky than anyone suspects. But regardless, at some point, this system still thinks the transaction has been authorized. I'm sure there's a huge audit log showing who/where/why the mistake was made. But I've also seen end-of-period processing at a smaller financial institution where humans are involved and a few spreadsheets hairpin their ways through different systems with lots of manual intervention and QA. One step was literally very close to "audit 0.01% of payments before sending the CSV into the lockbox escrow processing system...