Picker ItemDisplayBinding doesn't work as it is supposed to

[AmirImam]

Hi
I want to display a text in the picker according to the value. Like this:
Razor Code:
<Picker ItemsSource="worldsSource" ItemDisplayBinding=@(e=> e==null?"All":"+"+e.ToString()) />
C# Code:

//WorldTypes is an enum
private List<WorldTypes?> worldsSource = new()
    {
         null,WorldTypes.OpenWorld,WorldTypes.Linear,WorldTypes.Mix
    };

The result is correct in all values except the null one. It must appear as "All" text but it shows an empty text

Is there something wrong with my code?

[Dreamescaper]

Unfortunately, that seems to be MAUI's behavior. It doesn't even invoke this Func for null items.