Fix the failures in the Candidate branch- March 16

src/Controls/src/Core/Compatibility/Handlers/NavigationPage/iOS/NavigationRenderer.cs

@@ -986,14 +986,6 @@ void UpdateBarTextColor()
 						NavigationBar.BackIndicatorTransitionMaskImage = tinted;
 					}
 				}
-				else
-				{
-					NavigationBar.CompactAppearance.BackButtonAppearance = null;
-					NavigationBar.StandardAppearance.BackButtonAppearance = null;
-					NavigationBar.ScrollEdgeAppearance.BackButtonAppearance = null;
-					NavigationBar.BackIndicatorImage = null;
-					NavigationBar.BackIndicatorTransitionMaskImage = null;
-				}
 			}
 		}
 

src/Controls/src/Core/Handlers/Items/Android/ItemsSources/ObservableGroupedSource.cs

@@ -226,10 +226,9 @@ void UpdateGroupTracking()
 
 			for (int n = 0; n < _groupSource.Count; n++)
 			{
-				// Use ICollection (not IEnumerable) so that flat collections whose item type
-				// implements IEnumerable (e.g. string → IEnumerable<char>) are not mistaken
-				// for groups, which would render a header/footer per item.
-				if (_groupSource[n] is ICollection list)
+				var group = _groupSource[n];
+
+				if (group is IEnumerable list && group is not string) // Exclude string: it implements IEnumerable<char> but is a scalar value, not a group
 				{
 					var source = ItemsSourceFactory.Create(list, _groupableItemsView, this);
 					source.HasFooter = _hasGroupFooters;
@@ -294,10 +293,11 @@ void Add(NotifyCollectionChangedEventArgs args)
 
 			foreach (var item in args.NewItems)
 			{
-				// Count only real groups (ICollection); flat items like strings must not
-				// trigger a section insertion — they would cause _groups[groupIndex] to be
-				// out-of-range after UpdateGroupTracking skips non-ICollection items.
-				if (item is ICollection)
+				// Count only real groups (IEnumerable but not string); flat scalar items like strings
+				// must not trigger a section insertion — they would cause _groups[groupIndex] to be
+				// out-of-range after UpdateGroupTracking skips non-group items.
+				// string implements IEnumerable<char> but is a scalar value, not a group.
+				if (item is IEnumerable and not string)
 				{
 					count++;
 				}
@@ -332,10 +332,10 @@ void Remove(NotifyCollectionChangedEventArgs args)
 
 			foreach (var item in args.OldItems)
 			{
-				// Count only real groups (ICollection); flat items like strings must not
-				// trigger a section removal — they would cause _groups[groupIndex] to be
-				// out-of-range after UpdateGroupTracking skips non-ICollection items.
-				if (item is ICollection)
+				// Count only real groups (IEnumerable but not string); flat scalar items like strings
+				// must not trigger a section removal — they would cause _groups[groupIndex] to be
+				// out-of-range after UpdateGroupTracking skips non-group items.
+				if (item is IEnumerable and not string)
 				{
 					count++;
 				}

src/Controls/src/Core/Handlers/Items/iOS/ObservableGroupedSource.cs

@@ -133,7 +133,9 @@ void ResetGroupTracking()
 
 			for (int n = 0; n < _groupSource.Count; n++)
 			{
-				if (_groupSource[n] is INotifyCollectionChanged && _groupSource[n] is IEnumerable list)
+				var group = _groupSource[n];
+
+				if (group is INotifyCollectionChanged && group is IEnumerable list && group is not string)
 				{
 					_groups.Add(new ObservableItemsSource(list, controller, n));
 				}
@@ -240,14 +242,14 @@ void Add(NotifyCollectionChangedEventArgs args)
 				return;
 			}
 
-			// Only count items that are actual groups (ICollection); flat items like strings or model objects
-			// must not increment _groupCount or trigger InsertSections on UICollectionView
+			// Only count items that are actual groups (IEnumerable but not string); flat scalar items
+			// must not increment _groupCount or trigger InsertSections on UICollectionView.
+			// string implements IEnumerable<char> but represents a scalar value, not a group.
 			int count = 0;
 
 			foreach (var item in args.NewItems)
 			{
-				// Count only ICollection items — string and plain model objects are not groups
-				if (item is ICollection)
+				if (item is IEnumerable and not string)
 				{
 					count++;
 				}
@@ -288,14 +290,13 @@ void Remove(NotifyCollectionChangedEventArgs args)
 				return;
 			}
 
-			// Only count items that are actual groups (ICollection); flat items must not decrement
-			// _groupCount or trigger DeleteSections for sections that were never created
+			// Only count items that are actual groups (IEnumerable but not string); flat scalar items
+			// must not decrement _groupCount or trigger DeleteSections for sections that were never created.
 			int count = 0;
 
 			foreach (var item in args.OldItems)
 			{
-				// Count only ICollection items — string and plain model objects are not groups
-				if (item is ICollection)
+				if (item is IEnumerable and not string)
 				{
 					count++;
 				}
@@ -449,7 +450,9 @@ int GroupsCount()
 			{
 				foreach (var group in list)
 				{
-					if (group is ICollection)
+					// Accept any IEnumerable except string (string implements IEnumerable<char>
+					// but represents a scalar value, not a group).
+					if (group is IEnumerable and not string)
 					{
 						count++;
 					}
@@ -459,7 +462,7 @@ int GroupsCount()
 
 			foreach (var item in _groupSource)
 			{
-				if (item is ICollection)
+				if (item is IEnumerable and not string)
 				{
 					count++;
 				}

src/Controls/tests/TestCases.HostApp/Issues/Issue28656.xaml

@@ -2,15 +2,16 @@
 <ContentPage
     xmlns="http://schemas.microsoft.com/dotnet/2021/maui"
     xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
+     xmlns:local="clr-namespace:Maui.Controls.Sample"
     x:Class="Maui.Controls.Sample.Issues.Issue28656">
     <Grid RowDefinitions="Auto,*,*">
         <Button
             Command="{Binding ChangeLayoutCommand}"
             AutomationId="ChangeLayoutButton"
             Text="Change layout type"/>
-        <CollectionView Grid.Row="1"
+        <local:CollectionView2 Grid.Row="1"
                         ItemsSource="{Binding Items}">
-            <CollectionView.Triggers>
+            <local:CollectionView2.Triggers>
                 <DataTrigger
                     Binding="{Binding IsGridLayout}"
                     TargetType="CollectionView"
@@ -32,8 +33,8 @@
                         </Setter.Value>
                     </Setter>
                 </DataTrigger>
-            </CollectionView.Triggers>
-            <CollectionView.ItemTemplate>
+            </local:CollectionView2.Triggers>
+            <local:CollectionView2.ItemTemplate>
                 <DataTemplate x:DataType="{x:Null}">
                     <Grid>
                         <Grid
@@ -50,12 +51,12 @@
                     </Grid>
 
                 </DataTemplate>
-            </CollectionView.ItemTemplate>
-        </CollectionView>
-        <CollectionView Grid.Row="2"
+            </local:CollectionView2.ItemTemplate>
+        </local:CollectionView2>
+        <local:CollectionView2 Grid.Row="2"
                         ItemsLayout="{Binding ItemsLayout}"
                         ItemsSource="{Binding Items}">
-            <CollectionView.ItemTemplate>
+            <local:CollectionView2.ItemTemplate>
                 <DataTemplate x:DataType="{x:Null}">
                     <Grid>
                         <Grid
@@ -71,7 +72,7 @@
                         </Grid>
                     </Grid>
                 </DataTemplate>
-            </CollectionView.ItemTemplate>
-        </CollectionView>
+            </local:CollectionView2.ItemTemplate>
+        </local:CollectionView2>
     </Grid>
 </ContentPage>