Real-time QR update using Firebase

Question

I've been making a project in Xamarin.Forms that use Firebase (which for now only saves items) to make a list. I then retrieve and convert that list to string using IValueConverter, and I finally use that same string to convert it to QR code using ZXing.

In my code ItemViewPage.xaml, I used a CollectionView to check whether the database is updating in the first place.

My problem is that the QR code doesn't show until I remove and retype my binding in BarcodeValue during hot reload.

ItemViewPage.xaml:

<ContentPage.Resources>
    <ResourceDictionary>
        <local:CollectionConverter x:Key="CollectionConverter"/>
    </ResourceDictionary>
</ContentPage.Resources>

<ContentPage.Content>
    <StackLayout>
        <CollectionView ItemsSource="{Binding DatabaseItems}">
            <CollectionView.ItemTemplate>
                <DataTemplate>
                    <StackLayout>
                        <Label Text="{Binding Product}" FontSize="Large"/>
                    </StackLayout>
                </DataTemplate>
            </CollectionView.ItemTemplate>
        </CollectionView>

        <zxing:ZXingBarcodeImageView BarcodeValue="{Binding DatabaseItems, Converter={StaticResource CollectionConverter}}" WidthRequest="300" HeightRequest="300">
            <zxing:ZXingBarcodeImageView.BarcodeOptions>
                <zxingcommon:EncodingOptions Width="300" Height="300"/>
            </zxing:ZXingBarcodeImageView.BarcodeOptions>
        </zxing:ZXingBarcodeImageView>
    </StackLayout>
</ContentPage.Content>

ItemViewPage.xaml.cs:

namespace InventorySample.Views
{
    [XamlCompilation(XamlCompilationOptions.Compile)]
    public partial class ItemViewPage : ContentPage
    {
        public ObservableCollection<MyDatabaseRecord> DatabaseItems { get; set; } = new 
            ObservableCollection<MyDatabaseRecord>();


        readonly FirebaseClient firebaseClient = new FirebaseClient("https://inventorysample-eca49-default-rtdb.asia-southeast1.firebasedatabase.app/");

        public ItemViewPage()
        {
            InitializeComponent();
            BindingContext = this;

            var collection = firebaseClient
                .Child("Products")
                .AsObservable<MyDatabaseRecord>()
                .Subscribe((dbevent) =>
                {
                    if(dbevent.Object != null)
                    {
                        DatabaseItems.Add(dbevent.Object);
                    }
                }); 
        }
    }
}

CollectionConverter.cs

namespace InventorySample
{
    public class CollectionConverter : IValueConverter
    {
        public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
        {
            ObservableCollection<MyDatabaseRecord> Items = (ObservableCollection<MyDatabaseRecord>)value;

            var sb = new StringBuilder();
            foreach (var item in Items)
            {
                sb.AppendLine(item.Product);
            }
    
            return sb.ToString();
        }

        public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
        {
            return null;
        }
    }
}

I've already tried multiple things and am completely stumped. Hope someone can help. Thanks in advance.