I guess in FDM location -> Workflow behavior tab its is selected as Bulk insert
Why don't you try to select SQL insert and click import button
are you using SQL Server?
There is one document in Oracle Support
Error: "Bulk load data conversion error (type mismatch or invalid character for the specified codepage) for row 1, column 1 (PartitionKey)" (Doc ID 1085977.1)
That states Service Pack 3 is required for SQL Server to resolve this issue.
I hope that helps