MeasureFirstItem makes items disappear on Android

Description

I have a CollectionView where ItemSizingStrategy is set to MeasureFirstItem. The properties of the times are changed some time of the CollectionView is loaded. Somehow, this makes some items become invisible on Android. It works fine on Windows.

Originally, my list looks like this:

Then, the two first items should be changed to green. But the second one just disappears:

In Windows it’s works fine:

It’s very strange 😃

Steps to Reproduce

1. Create a new Maui app.
2. Change MainPage.xaml to:

<?xml version="1.0" encoding="utf-8" ?>
<ContentPage xmlns="http://schemas.microsoft.com/dotnet/2021/maui"
             xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
             xmlns:v="clr-namespace:MauiIssues"
             x:Class="MauiIssues.MainPage"
             >
    <Grid>
        <CollectionView ItemsSource="{Binding Issues}" ItemSizingStrategy="MeasureFirstItem">
            <CollectionView.ItemTemplate>
                <DataTemplate>
                    <Grid>
                        <Label Text="{Binding Title, Mode=OneWay}"
                            TextColor="Red"
                            IsVisible="{Binding IsRed}"
                                />

                        <Label Text="{Binding Title, Mode=OneWay}"
                            TextColor="Green"
                            IsVisible="{Binding IsGreen}}"
                                />
                    </Grid>
                </DataTemplate>
            </CollectionView.ItemTemplate>
        </CollectionView>
    </Grid>
</ContentPage>

1. Change MainPage.cs to:

using System.Collections.ObjectModel;

namespace MauiIssues;

public partial class MainPage : ContentPage
{
    public MainPage()
    {
        InitializeComponent();

        BindingContext = this;
    }

    public class Issue : BindableObject
    {
        public string Title { get; set; }
        public bool IsRed { get; set; } = true;
        public bool IsGreen => !IsRed;

        public void MakeGreen()
        {
            IsRed = false;
            OnPropertyChanged(nameof(IsGreen));
            OnPropertyChanged(nameof(IsRed));
        }
    }

    public ObservableCollection<Issue> Issues { get; } = new ObservableCollection<Issue>();

    protected async override void OnAppearing()
    {
        base.OnAppearing();

        Issues.Add(new Issue { Title = "Issue 1" });
        Issues.Add(new Issue { Title = "Issue 2" });
        Issues.Add(new Issue { Title = "Issue 3" });

        await Task.Delay(4000);

        Issues[0].MakeGreen();
        Issues[1].MakeGreen();
    }
}

Run the project in Android.

Full sample code: https://github.com/pekspro/MauiIssues/tree/7562_MeasureFirstItem_makes_items_disappear

Version with bug

6.0 (current)

Last version that worked well

Unknown/Other

Affected platforms

Android

Affected platform versions

Windows 10.0.17763.0, Android 11

Did you find any workaround?

Removing ItemSizingStrategy="MeasureFirstItem" solves the problem.

Relevant log output

No response

[pekspro]

I’ve updated sample application to .NET 7. The same issue remains. I have also tried the work around from @ToolmakerSteve, but it didn’t helped.

[jvakos]

Bug remains in dotnet 8.0.0-preview.6.8686.