ADFS 2012 R2 - Event ID 364 with MFA

I've got a SAML RP configured with a POST binding.

This endpoint is using MFA which works internally, but when hitting the WAP from the outside network, I get a an event id 364 that says:

Exception details: 
Microsoft.IdentityServer.RequestFailedException: No strong authentication method found for the request from https://XXXXXX.[redacted]
   at Microsoft.IdentityServer.Web.PassiveProtocolListener.CheckAuthenticationOptionsForMethods(ProtocolContext context, List`1 authMethods)
   at Microsoft.IdentityServer.Web.PassiveProtocolListener.OnGetContext(WrappedHttpListenerContext context)

Does anyone have any insight into this?

Regards

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G. Samuel Hays, MCT, MCSE 2012, MCITP: Enterprise Admin

Blog:gsamuelhays.blogspot.com

twitter:twitter.com/gsamuelhays