Can you provide the sample data (csv files) or the tableau workbook so that it will be easier to have a look?
It looks like Tableau can't find the header row in that CSV file. Is there a header row, and does it use the same delimiter as the data rows?
We may be able to help more if you attach the two CSV files. If they contain sensitive data, you could attach copies with only a few rows of mock data.
please see the workbook I've now attached.