Why does Xamarin.Forms databinding work for one control but not another? - xaml

Question

I am developing a Xamarin app which I am testing on an Android device. I have a XAML view and I am binding an enum property in the viewmodel to multiple controls - one for text value, and the other to background color with an IValueConverter. Relevant XAML code:
<ContentView
BackgroundColor="{Binding MyField, Converter={StaticResource MyFieldEnumValueToColorConverter}}"
>
<ContentView.GestureRecognizers>
<TapGestureRecognizer
Command="{Binding MyFieldClickCommand}" />
</ContentView.GestureRecognizers>
<Label
Text="{Binding MyField}"
/>
</ContentView>
IValueConverter implementation:
public class MyFieldEnumValueToColorConverter : IValueConverter
{
public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
{
if (value is MyFieldEnum)
{
switch ((MyFieldEnum)value)
{
case MyFieldEnum.Value1:
return Color.Orange;
case MyFieldEnum.Value2:
return Color.Green;
case MyFieldEnum.Value3:
return Color.Red;
}
}
return Color.White;
}
public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
{
throw new NotImplementedException();
}
}
Property in the viewmodel (yes, it does implement INotifyPropertyChanged):
public event PropertyChangedEventHandler PropertyChanged;
private MyFieldEnum _myField;
public MyFieldEnum MyField
{
get => _myField;
set
{
_myField= value;
PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(nameof(MyField)));
}
}
When I load this page, the controls load properly for every distinct enum value: the text and the background color both reflect the actual value.
In a click handler, I simply set the property value like this:
MyField = MyFieldEnum.Value2;
The text changes, but the background color does not. Why?
I also tried introducing a new field (of type Color), implement the IValueConverter logic directly in the getter, and bind that to the BackgroundColor attribute of the ContentView. Same issue. The page has many other data-bound items and all work properly except this one.
UPDATE: it appears that the problem is with the ContentView. I put the exact same BackgroundColor binding to the Label itself and there it works as expected, but for the ContentView it does not.