Migrated Creo CAD Files Downloading with .PHA Extension Instead of .PRT

I am using Windchill Bulk Migrator Release 13.1 and Datecode with CPS 13.1.2.0 We are performing a CAD data migration using Windchill Bulk Migrator (WBM) from a source Windchill system to a target Windchill 13.1.2.0 system. The migration involves CAD files such as Creo .PRT files. The physical CAD content is successfully copied/moved to the target vault and the file is present at the expected target file path with the expected physical filename. However, when the primary CAD content is downloaded from the target Windchill UI, the downloaded file is given a .PHA extension instead of the expected .PRT extension. Please advise how to correctly migrate/load the CAD content so that a Creo .PRT file is downloaded with the correct .PRT extension.