2529055 - "User already exists" validation error when creating new user but user does not exist in LMS

While creating a new user account in LMS we receive a validation error that states:

Validation Error

You must correct the following error(s) before proceeding:

• The user (user_name) already exists. Please create another one. You can configure user IDs so that they are not case sensitive

However, this user cannot be found anywhere in the system. Searching all active and inactive Users returns no results.

SuccessFactors Learning Management System (LMS) - All Supported Versions

User Already exists, Validation error, LRN-17276, PA_STUDENT, PA_STUD_SELF_REGISTRATION, User Created accounts , KBA , LOD-SF-LMS-ADM , System Admin, Global Variables, References , How To