Привязка .NET MAUI к GraphicsView

У меня проблемы с пониманием того, как работает привязка в .NET MAUI. Моя цель состоит в том, чтобы иметь два способа отображения оценки внутри CollectionView: метка с числом и графическое представление. Привязка партитуры к метке работает нормально, а вот привязка к Drawable — нет. Если я пишу число вместо использования привязки, оно передается просто отлично.

Что я делаю не так?

ПроцедурыPage.xaml

<?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:model = "clr-namespace:MediSkillApp.Model"
             xmlns:drawables = "clr-namespace:MediSkillApp.Drawables"
             xmlns:viewmodel = "clr-namespace:MediSkillApp.ViewModel"
             x:Class = "MediSkillApp.View.ProceduresPage"
             x:DataType = "viewmodel:ProceduresViewModel"
             Title = "Alle mine indgreb">

    <Grid ColumnDefinitions = "*"
          ColumnSpacing = "5"
          RowSpacing = "0">

        <CollectionView
            BackgroundColor = "Transparent"
            ItemsSource = "{Binding Procedures}"
            RemainingItemsThresholdReachedCommand = "{Binding GetProceduresCommand}"
            RemainingItemsThreshold = "5">
            <CollectionView.ItemTemplate>
                <DataTemplate x:DataType = "model:Procedure">
                    <VerticalStackLayout>
                        <Frame Margin = "5">
                            <Grid ColumnDefinitions = "64,*, 64">
                                <Image 
                                    Grid.Column = "0"
                                    Source = "{Binding Icon}"
                                    HeightRequest = "48"
                                    WidthRequest = "48"
                                    HorizontalOptions = "Start"/>
                                
                                <VerticalStackLayout
                                    Grid.Column = "1">
                                    <Label Text = "{Binding ProcedureTypeString}"
                                           Style = "{StaticResource Heading}"/>
                                    <Label Text = "{Binding OpRoleString}"
                                           Style = "{StaticResource NormalLabel}"/>
                                    <Label Text = "{Binding Date, StringFormat='{0:dd/MM-yyyy}'}"
                                           Style = "{StaticResource NormalLabel}"/>
                                </VerticalStackLayout>
                                
                                <VerticalStackLayout
                                    Grid.Column = "2"
                                    IsVisible = "{Binding IsScored}">

                                    <!-- this binding works -->
                                    <Label Text = "{Binding AvgScore, StringFormat='{0:F2}'}" 
                                           HorizontalOptions = "Center"/>

                                    <Image Source = "scoremeter.png"/>
                                    
                                    <GraphicsView>
                                        <GraphicsView.Drawable>

                                            <!-- this binding does not -->
                                            <drawables:ScoreGaugeDrawable
                                                    Score = "{Binding AvgScore}"/>
                                        </GraphicsView.Drawable>
                                    </GraphicsView>
                                </VerticalStackLayout>
                            </Grid>
                        </Frame>
                    </VerticalStackLayout>

                </DataTemplate>
            </CollectionView.ItemTemplate>
        </CollectionView>

        <ActivityIndicator IsVisible = "{Binding IsBusy}"
                           IsRunning = "{Binding IsBusy}"
                           HorizontalOptions = "FillAndExpand"
                           VerticalOptions = "CenterAndExpand"/>
    </Grid>
    
    
</ContentPage>

ScoreGaugeDrawable.cs

namespace MediSkillApp.Drawables;

public class ScoreGaugeDrawable : BindableObject, IDrawable
{
    public static readonly BindableProperty ScoreProperty = BindableProperty.Create(nameof(Score),
        typeof(double),
        typeof(ScoreGaugeDrawable));

    public double Score {
        get => (double)GetValue(ScoreProperty);
        set => SetValue(ScoreProperty, value);
    }

    public void Draw(ICanvas canvas, RectF dirtyRect)
    {
        var centerPoint = new PointF(32, 0);
        var circleRadius = 5;

        canvas.FillColor = Colors.Black;
        canvas.FillCircle(centerPoint, circleRadius);

        canvas.StrokeColor = Colors.Black;
        canvas.DrawLine(centerPoint, new Point(0, Score * 10)); //Just draw something for testing
    }
}

Процедура.cs

namespace MediSkillApp.Model;

public class Procedure
{
    public string Identifier { get; set; }
    public DateTime Date { get; set; }
    public string GetDate {
        get => Date.ToString("d/M-yyyy");
    }

    public int ProcedureType { get; set; }
    public string ProcedureTypeString { get; set; }
    public double AvgScore { get; set; }

    public string GetAvgScore {
        get {
            if (AvgScore == 0) return "";
            return AvgScore.ToString();
        }
    }

    public int OpRole { get; set; }
    public string OpRoleString { get; set; }

    public string Icon {
        get {
            switch (ProcedureType) {
                case 7:
                    return Icons.IconBleed;
                case 8:
                    return Icons.IconTEA;
                case 18:
                    return Icons.IconTEA;
                default:
                    return Icons.IconSurgery;
            }
        }
    }

    public bool IsScored => AvgScore > 0;
}

ПроцедурыViewModel.cs

using MediSkillApp.Model;
using MediSkillApp.Services;

namespace MediSkillApp.ViewModel;

public partial class ProceduresViewModel : BaseViewModel
{
    public ObservableCollection<Procedure> Procedures { get; } = new();
    private APIService APIservice;

    public ProceduresViewModel(APIService aPIservice) {
        APIservice = aPIservice;
    }

    [RelayCommand]
    public async Task GetProceduresAsync() {
        if (IsBusy) return;

        try {
            IsBusy = true;
            var procedures = await APIservice.GetProceduresAsync("8", "dawda", Procedures.Count, 15);

            foreach (Procedure procedure in procedures) {
                Procedures.Add(procedure);
            }
        } catch(Exception ex) {
            Debug.WriteLine(ex);
        } finally {
            IsBusy = false;
        }
    }

    public void ClearProcedures() {
        Procedures.Clear();
    }
}