Migration fails at a row (no replies)

Hey all
Im having a rather strange issue using MySQL Workbench to migrate from Microsoft SQL to MySQL.

Ive setup the table correctly in MySQL, with matching data types etc, so I doubt thats the issue.

The moment I run the migration, rows start being copied over. This runs fine until a certain point (in this case certain ROW), where I get this error:

ERROR:`mysql_database_schema_name.`mysql_database_table`:basic_string::substr

AND the migration fails right there.

I've tried this migration with a different data set from Microsoft SQL, and the same error occurs, only at a different row.

Any ideas?