ADFS 3.0 - implicitUPN attribute not returned in attribute cache

I am trying to use claims based authentication through a relying party trust. I am getting two warnings in the ADFS debug logs:

1.  The implicitUPN retrieved for Active Directory account "DOMAIN\USERNAME" was empty (Code 53)
2. LDAPAttributeStoreReader: Attribute value for claimType http://shcemas.microsoft.com/ws/2007/08/ldap/implicitUPN is not found in attribute cache (Code 23)

I am suspecting this is causing downstream issues where I cannot use the resulting claim that is being returned to my .NET application.

The active directory user does have a valid UPN attribute.

Operating against:

Server 2012 R2 ADFS 3.0

ADFS Authentication against Active Directory

Any thoughts or suggestions?