Issue Summary

Assets csv import throws an error message if you have a User attribute being mapped as an identifier in the import configuration.

Steps to Reproduce

1. Create a User attribute type in one of your schemas.
2. Setup a csv import and tag that attribute as an identifier while mapping your import.

Expected Results

The import should successfully import your data.

Actual Results

The import throws the following error message and no data is imported:

x error(s) found in source data

Workaround

Select other attribute type as an identifier in your import configuration.