Systems and methods for use in monitoring authentication messaging associated with payment account transactions are disclosed. One exemplary method includes monitoring authentication messaging from a merchant plug-in (MPI) associated with at least one merchant. The authentication messaging is related to one or more consumers attempting transactions to payment accounts at the at least one merchant. The exemplary method further includes, for each authentication message received from the MPI, transmitting the authentication message to an access control server (ACS) when an issuer associated with the payment account at issue is a participant in an authentication service, monitoring, by the computing device, response messaging from the ACS, each response message associated with a transaction and generated in response to an authentication messages from the MPI, and generating, by the computing device, at least one flag, when a condition associated with the authentication messages and/or the response messages is abnormal.