HDL error when adding roles to employee using UserRole.dat (User/UserRole Business Object)

Summary:

We are trying to bulk assign roles to an employee using the HCM Data Loader (HDL) User/UserRole business objects, but the process consistently fails with DLOAD_PROCESS_BIZ_ERROR and ds_transfer_error during the import stage.
The HDL file (UserRole.zip) is formatted correctly, UTF-8 encoded, and uploaded successfully, but the job fails before any row-level validation messages appear.

Content (please ensure you mask any confidential information):

Scenario:
We are testing the assignment of multiple roles to an existing employee (Person Number 14475) using HCM Data Loader.

The UserRole.dat structure used is as follows:

METADATA|User|PersonNumber  MERGE|User|14475  METADATA|UserRole|PersonNumber|RoleCommonName|AddRemoveRole  MERGE|UserRole|14475|ORA_PER_EMPLOYEE_ABSTRACT|ADD