using (var ts =  new TransactionScope(TransactionScopeOption.Required, new TransactionOptions(), TransactionScopeAsyncFlowOption.Enabled))
{
    var dbConnection = factory.CreateConnection();
    if (dbConnection == null)
        return;
    dbConnection.ConnectionString = connectionStrings;
    await dbConnection.EnsureOpenAsync();
    var timestamp = DateTimeOffset.UtcNow;
    var defaultTimeStamp = new DateTimeOffset(new DateTime(1900, 1, 1));
    // OK
    await dbConnection.InsertAsync(new User
    {
        Id = 1,
        Name = "user1",
        Email = "email",
        CreatedAt = timestamp,
        UpdatedAt = timestamp,
        DeletedAt = defaultTimeStamp
    });

    // NG Throws System.NullReferenceException
    await dbConnection.InsertAllAsync(new[]
    {
        new User { Id = 2, Name = "user2", Email = "email", CreatedAt = timestamp, UpdatedAt = timestamp, DeletedAt = defaultTimeStamp},
        new User { Id = 3, Name = "user3", Email = "email", CreatedAt = timestamp, UpdatedAt = timestamp, DeletedAt = defaultTimeStamp},
        new User { Id = 4, Name = "user4", Email = "email", CreatedAt = timestamp, UpdatedAt = timestamp, DeletedAt = defaultTimeStamp},
        new User { Id = 5, Name = "user5", Email = "email", CreatedAt = timestamp, UpdatedAt = timestamp, DeletedAt = defaultTimeStamp},
        new User { Id = 6, Name = "user6", Email = "email", CreatedAt = timestamp, UpdatedAt = timestamp, DeletedAt = defaultTimeStamp},
        new User { Id = 7, Name = "user7", Email = "email", CreatedAt = timestamp, UpdatedAt = timestamp, DeletedAt = defaultTimeStamp},
        new User { Id = 8, Name = "user8", Email = "email", CreatedAt = timestamp, UpdatedAt = timestamp, DeletedAt = defaultTimeStamp},
        new User { Id = 9, Name = "user9", Email = "email", CreatedAt = timestamp, UpdatedAt = timestamp, DeletedAt = defaultTimeStamp},
        new User { Id = 10, Name = "user10", Email = "email", CreatedAt = timestamp, UpdatedAt = timestamp, DeletedAt = defaultTimeStamp}
    });
    ts.Complete();
    await dbConnection.CloseAsync();
}