File downloaded for an archived job in ManTra is not a Target File but a summary file with the source file extension.

Download the Archived Job Data from TMS and the zip downloaded contains all files including the target file as expected. However, go to ManTra --> search for the job and click on Download, only a summary file with the format of source file is downloaded.

Defect CRQ-30897 was raised to Development team to fix this issue. Issue has been fixed in customisations with version 12.6.34636.0 or higher.
 

Another way to download the Target File of Archived job is:
Users must download the Archived Job Data from TMS directly.

Knowledge article SDL TMS: How to see an Archived job and download files? explains how to see an Archived job in TMS and download the files.

If the users do not have access to TMS, raise a ticket to RWS Support from Gateway so Support team can download the archived job data files.

Defect CRQ-30897 was raised to Development team to fix this issue. Issue has been fixed in customisations with version 12.6.34636.0 or higher.