Why a 3D Secure 2 payment was Authorised with transStatus: A : Attempted to Authenticate from the ARes and without a challenge?

transStatus: A is an authentication response from the schemes (Mastercard, Visa) to inform the merchant that this transaction attempted Authentication however, at this stage the issuer was not ready or able to perform a strongAuthentication (ie. OTP/Password). Such transactions, when the schemes step in, do come with a successful liability shift.