Comment by kukkeliskuu

Having worked as the lead architect for bank core payment systems, multiple bank scenario is a special case that is way too complex for the purpose of these discussions.

It is a multi-layered processes that ultimately makes it very probable that the state of a payment transaction is consistent between banks, involving reconciliation processes, manual handling of failed transactions over extended time period if the reconciliation fails, settlement accounts for each of the involved banks and sometimes even central banks for instant payments.

But I can imagine scenarios when even those can fail to make the transaction state globally consistent. For example a catastrophic event that destroys the bank's systems and a small bank has failed to take off-site backups, and one payment has some hic-up so that the receiving bank cannot know what happened with the transaction. So they would probably assume something.