Mandatory “Last Name” Field Not Validated During CSV Upload

When uploading a CSV file, even if the Last Name field is empty (though it is marked as mandatory), the system does not display any validation error. Instead, the upload is marked as successful, and the record is created in the system.

env: pre-release and prod
org : Testdin (prod)
user : dinesh@Testdin

Steps to Reproduce:

1.Prepare a CSV file with the Last Name field left empty for one or more records
2.Upload the CSV file through the bulk upload option
3.Submit the file

Expected Result:

System should throw a validation error.Error message should indicate that “Last Name is mandatory”.Record should NOT be created

Actual result :

No validation error is displayed. Upload shows success message . Record is created with empty Last Name field

Reference files ;

uploaded file :

[sample-Subject---Test person.csv](https://github.com/user-attachments/files/25281781/sample-Subject---Test.person.csv)

Start with the backend bulk-upload flow for CSV files and reproduce the issue using the attached sample-Subject---Test.person.csv, leaving Last Name empty. Trace where mandatory-field validation and record creation are handled; done means the upload reports that Last Name is mandatory and does not create the record.

Written by the indexing model from the issue text.