textbox and label not immediatly showing up after button click

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Drawing;
using System.Windows.Forms;

namespace WinFormsApp1
{
    internal class CreateNewCustomerTab
    {
        internal static void CreateNewCustomer(TabControl tabControl, string tabName)
        {
            // Create a new TabPage
            TabPage newTab = new TabPage(tabName);

            // Create controls: Label and TextBox for Account Number
            Label acctNumLabel = new Label();
            acctNumLabel.Text = "Account Number:";
            acctNumLabel.Width = 300;
            acctNumLabel.ForeColor = Color.Black;
            acctNumLabel.Location = new Point(38, 15);

            TextBox acctNumTextBox = new TextBox();
            acctNumTextBox.Location = new Point(56, 22);
            acctNumTextBox.Name = "acctNumTextBox";
            acctNumTextBox.Enabled = false; // Prevent user input
            acctNumTextBox.ReadOnly = true; // Read-only

            // Generate a random account number and display it in the TextBox
            Random random = new Random();
            int accountNumber = random.Next(1000, 10000); // Change this range as needed
            acctNumTextBox.Text = accountNumber.ToString();

            // Add controls to the new tab's Controls collection
            newTab.Controls.Add(acctNumLabel);
            newTab.Controls.Add(acctNumTextBox);

            // Add the new tab to the TabControl
            tabControl.TabPages.Add(newTab);


            // Show the newly added tab immediately
            tabControl.SelectedTab = newTab;

            // Refresh the control
            tabControl.Refresh();
        }
    }
}

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Drawing;
using System.Windows.Forms;

namespace WinFormsApp1
{
    internal class CreateNewCustomerTab
    {
        internal static void CreateNewCustomer(TabControl tabControl, string tabName)
        {
            // Create a new TabPage
            TabPage newTab = new TabPage(tabName);

            // Create controls: Label and TextBox for Account Number
            Label acctNumLabel = new Label();
            acctNumLabel.Text = "Account Number:";
            acctNumLabel.Width = 300;
            acctNumLabel.ForeColor = Color.Black;
            acctNumLabel.Location = new Point(38, 15);

            TextBox acctNumTextBox = new TextBox();
            acctNumTextBox.Location = new Point(56, 22);
            acctNumTextBox.Name = "acctNumTextBox";
            acctNumTextBox.Enabled = false; // Prevent user input
            acctNumTextBox.ReadOnly = true; // Read-only

            // Generate a random account number and display it in the TextBox
            Random random = new Random();
            int accountNumber = random.Next(1000, 10000); // Change this range as needed
            acctNumTextBox.Text = accountNumber.ToString();

            // Add controls to the new tab's Controls collection
            newTab.Controls.Add(acctNumLabel);
            newTab.Controls.Add(acctNumTextBox);

            // Add the new tab to the TabControl
            tabControl.TabPages.Add(newTab);


            // Show the newly added tab immediately
            tabControl.SelectedTab = newTab;

            // Refresh the control
            tabControl.Refresh();
        }
    }
}