UPM Failing for account with error "The specified account does not exist."

Users not receiving a UPM profile when logging into application. When logging in UPM fails, within the UPM logs we only see the following logged :- 2016-08-25;14:11:45.659;INFORMATION;EXTRANET;x9027690;3;15276;CADUser::Init: Determined user and DNS domain name: ,...