I am certain it's not person error, since the recovery phrase was present in two unique areas: backed up in a file on S3, and printed with a piece of paper. This text describes BIP39, the standard that defines how seed phrases are created, and summarizes how BIP32 and BIP44 http://collinmmss433.lucialpiazzale.com/opening-the-power-of-bip39-a-comprehensive-check-out-word-lists-and-secure-pocketbooks