CSV Inconsistent formatting

[JacDsc]

.NET Framework 4.8, CSVHelper 34.0.1
I would like to set a format for all DateTime values (yyyy-MM-dd, no time info). The solutions suggested here and on SO work on CSVHelper on .NET Core, but fail as indicated in my sample code:

        public static void Main()
        {
            var records = new List<Test>
            {
                new Test { Id = 1, Name = "Spagaña, Antonio", ReceivedDate = DateTime.Parse("3/22/1972"), OptDate = DateTime.Parse("4/2/22") },
                new Test { Id = 2, Name = "two", ReceivedDate = DateTime.Parse("1/23/1998"), OptDate=new DateTime(1982, 3, 22) },
            };
            var fileBytes = Array.Empty<byte>();

            using (var stream = new MemoryStream())
            {
                using (var writer = new StreamWriter(stream, Encoding.UTF8))
                {
                    using (var csv = new CsvWriter(writer, new CsvConfiguration(CultureInfo.InvariantCulture)))
                    {
                        csv.Context.RegisterClassMap(new TestMap());
                        csv.WriteRecords(records);

                    }
                }
                fileBytes = stream.ToArray();
            }

            HttpContext current = HttpContext.Current;
            current.Trace.IsEnabled = false;
            current.Response.Clear();
            current.Response.ContentType = "application/octet-stream"; // or application/force-download
            current.Response.AddHeader("content-disposition", "attachment;    filename=SelectedRecords.csv");
            current.Response.BinaryWrite(fileBytes);
            current.Response.End();
        }
        public class Test
        {
            public int Id { get; set; }

            public string Name { get; set; }

            public DateTime ReceivedDate { get; set; }
            public DateTime? OptDate { get; set; }
        }
        public class TestMap : ClassMap<Test>
        {
            public TestMap()
            {
                var csvContext = new CsvContext(new CsvConfiguration(CultureInfo.InvariantCulture));
                // 'Works', correctly formatted as specified
                // Id,Name,ReceivedDate,OptDate
                //  1,"Spagaña, Antonio",1972=03=22,2022=04=02
                //  2,two,1998=01=23,1982=03=22
                //csvContext.TypeConverterOptionsCache.GetOptions<DateTime>().Formats = new[] { "yyyy=MM=dd" };
                //csvContext.TypeConverterOptionsCache.GetOptions<DateTime?>().Formats = new[] { "yyyy=MM=dd" };

                // Fails, returning original unformatted input values
                // Id Name    ReceivedDate OptDate
                //  1   Spagaña, Antonio    3/22/1972   4/2/2022
                //  2   two 1/23/1998   3/22/1982
                csvContext.TypeConverterOptionsCache.GetOptions<DateTime>().Formats = new[] { "yyyy-MM-dd" };
                csvContext.TypeConverterOptionsCache.GetOptions<DateTime?>().Formats = new[] { "yyyy-MM-dd" };

                AutoMap(csvContext);
            }
        }