Derived Column transformation in ssis - Resolve issue with embedded delimiters

I am creating a package to resolve an issue with embedded comma delimiters within columns in a csv file, by changing the delimiter from comma to pipe. Upon applying theREPLACE([FieldName],"\",\"","\"|\"") derived column transformation, my destination file loses about 160,000 rows from the source file.

The source file is being read as one column and the destination file also has one column.

Is there any obvious reason why this is happening ?

thanks

Scott