Fix ShellItems and MenuItems not displaying on Android when Flyout is presented, for both custom and default templates

src/Controls/src/Core/Compatibility/Handlers/Shell/Android/ShellFlyoutTemplatedContentRenderer.cs

@@ -439,7 +439,7 @@ void OnFlyoutViewLayoutChanging()
 			// The second time this fires the non flyout part of the view
 			// is visible to the user. I haven't found a better
 			// mechanism to wire into in order to detect this
-			if ((_initialLayoutChangeFired || FlyoutView.FlyoutBehavior == FlyoutBehavior.Locked) &&
+			if ((_initialLayoutChangeFired || FlyoutView.FlyoutBehavior == FlyoutBehavior.Locked || _shellContext.Shell.FlyoutIsPresented) &&
 				_flyoutContentView == null)
 			{
 				UpdateFlyoutContent();

src/Controls/tests/TestCases.HostApp/Issues/Issue21963.cs

@@ -0,0 +1,127 @@
+namespace Maui.Controls.Sample.Issues;
+
+[Issue(IssueTracker.Github, 21963, "ShellMenuItemTemplate Sometime Does Not Work", PlatformAffected.Android)]
+public partial class Issue21963 : TestShell
+{
+
+	protected override void Init()
+	{
+		this.FlyoutIsPresented = true;
+		this.ItemTemplate = new DataTemplate(() =>
+		{
+			var content = new ContentView();
+			var label = new Label();
+			label.SetBinding(Label.TextProperty, "Title");
+			content.Content = label;
+
+			return content;
+		});
+
+		// MenuItemTemplate
+		this.MenuItemTemplate = new DataTemplate(() =>
+		{
+			var content = new ContentView();
+			var label = new Label();
+			label.SetBinding(Label.TextProperty, "Title");
+			content.Content = label;
+
+			return content;
+		});
+
+		// ShellContent 1
+		var shellContent1 = new ShellContent
+		{
+			Title = "ShellContent 1",
+			AutomationId = "Issue21963ShellContent1",
+			ContentTemplate = new DataTemplate(typeof(Issues.Issue21963InnerPage))
+		};
+
+		// ShellContent 2
+		var shellContent2 = new ShellContent
+		{
+			Title = "ShellContent 2",
+			AutomationId = "Issue21963ShellContent2",
+			ContentTemplate = new DataTemplate(typeof(Issues.Issue21963MenuPage))
+		};
+
+		// ShellContent 3
+		var shellContent3 = new ShellContent
+		{
+			Title = "ShellContent 3",
+			AutomationId = "Issue21963ShellContent3",
+			ContentTemplate = new DataTemplate(typeof(Issues.Issue21963FlyoutPage))
+		};
+
+		// MenuItems
+		var menuItem1 = new MenuItem
+		{
+			Text = "MenuItem 1",
+			AutomationId = "Issue21963MenuItem1"
+		};
+
+		var menuItem2 = new MenuItem
+		{
+			Text = "MenuItem 2",
+			AutomationId = "Issue21963MenuItem2"
+		};
+
+		// Add items to Shell
+		Items.Add(shellContent1);
+		Items.Add(shellContent2);
+		Items.Add(shellContent3);
+
+		Items.Add(menuItem1);
+		Items.Add(menuItem2);
+	}
+}
+
+public class Issue21963InnerPage : ContentPage
+{
+	public Issue21963InnerPage()
+	{
+		Content = new VerticalStackLayout
+		{
+			Children =
+			{
+				new Button
+				{
+				Text = "Click Me"
+				}
+			}
+		};
+	}
+}
+
+public class Issue21963MenuPage : ContentPage
+{
+	public Issue21963MenuPage()
+	{
+		Content = new VerticalStackLayout
+		{
+			Children =
+			{
+				new Button
+				{
+				Text = "Click Me"
+				}
+			}
+		};
+	}
+}
+public class Issue21963FlyoutPage : ContentPage
+{
+	public Issue21963FlyoutPage()
+	{
+		Content = new VerticalStackLayout
+		{
+			Children =
+			{
+				new Button
+				{
+				Text = "Click Me"
+				}
+			}
+		};
+	}
+}
+

src/Controls/tests/TestCases.Shared.Tests/Tests/Issues/Issue21963.cs

@@ -0,0 +1,28 @@
+#if TEST_FAILS_ON_WINDOWS// This test fails on Windows: Shell.MenuItemTemplate behaves correctly,AutomationId does not work as expected on the Windows platform.
+using NUnit.Framework;
+using UITest.Appium;
+using UITest.Core;
+
+namespace Microsoft.Maui.TestCases.Tests.Issues;
+
+public class Issue21963 : _IssuesUITest
+{
+    public Issue21963(TestDevice testDevice) : base(testDevice)
+    {
+    }
+
+    public override string Issue => "ShellMenuItemTemplate Sometime Does Not Work";
+
+    [Test]
+    [Category(UITestCategories.Shell)]
+    public void VerifyFlyoutAndTemplatesPresentInitially()
+    {
+        App.WaitForElement("ShellContent 1");
+        App.WaitForElement("ShellContent 2");
+        App.WaitForElement("MenuItem 1");
+        App.WaitForElement("MenuItem 2");
+        App.WaitForElement("ShellContent 3");
+
+    }
+}
+#endif