Created Unassigned: Date/Number Formatting Issue using Worksheets.Add [9377]

I am using the workbook.worksheets.add method with a data table that I get from an Oracle DB using ODP.NET, but numbers and dates are always formatted as text. I end up running methods to fix this, but typically they require lots of memory to work.

code snippet:

XLWorkbook xlwb = new XLWorkbook();
IXLWorksheet ws = xlwb.Worksheets.Add(dt, "Worksheet Name");