Why doesn't EF populate the value?

Question

.NET

ASP Core project with EF Core.
In Context Code

modelBuilder.Entity<Table>(option => {
                option.Property(p => p.Guid)
                .ValueGeneratedOnAdd()
                .IsRequired();
            });

that is in the field Guid value.
It doesn't work, writes cannot insert the value null into column Guid
Ok. I put the attribute [DatabaseGenerated(DatabaseGeneratedOption.Identity)] to the field in the model.
cannot insert the value null into column Guid
Ok.

var newTable = new Table()
newTable.Guid = new Guid();
context.MyTables.Add(newTable);
context.SaveChanges();

cannot insert the value null into column Guid

Answer 1

In the third example, new Guid()use - instead Guid.NewGuid()- the default constructor always returns a null GUID.