C# BulkCopy column mappings don't work with IDataReader

We're using C# ADO 15.7 SDK SP122

and we've found the C# BulkCopy column mappings don't work with IDataReader.

If we set up the mappings (AseBulkCopyMapping) and use WriteToServer(DataTable) it all works correctly.

If we use WriteToServer(IDataReader) then the mappings are ignored.

Comparing the code AseBulkCopyBusinessBulk(IDataReader reader, AseBulkCopy bulkCopy, int batchSize)

to AseBulkCopyBusinessBulk(DataTable table, DataRowState rowState, AseBulkCopy bulkCopy, int batchSize)

there's code to handle the mappings for DataTable.

Am I reading this correctly ? Is this fixed in a later version ?

Thanks