Issue with Formatting nullable column in DB

[alwinthambi]

Hello, Josh am setting the format for decimal/date columns like this, but it does not work if the column is nullable in the DB.
Attached is the image where -22338403.39000000 is not formatted as its a nullable column in the DB.
_log.Info(string.Format("Started creating the files...{0}", fileNameWithPath));

            using (var writer = new StreamWriter(fileNameWithPath))
            using (var csv = new CsvWriter(writer))
            {
                
                csv.Configuration.RegisterClassMap(mapType);
                csv.Configuration.TypeConverterOptionsCache.GetOptions<decimal>().Formats = new[] { "N8" };
                csv.Configuration.TypeConverterOptionsCache.GetOptions<DateTime>().Formats = new[] { "MM-dd-yyyy" };
                csv.WriteRecords(records);
                
            }