TextBoxRegex doesn't work within a TabViewItem

[FrancoisM]

this alone in a page works:

<StackPanel>
                    <TextBox Header="Nom" Text="{Binding Nom, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}"
                         extensions:TextBoxRegex.Regex="{x:Bind NomRegex}"
                         extensions:TextBoxRegex.ValidationMode="Forced" 
                         Background="{Binding (extensions:TextBoxRegex.IsValid), RelativeSource={RelativeSource Self}, Converter={StaticResource ValidationConverter}}"
                         Style="{StaticResource InputStyle}"/>
                    <Button Content="OK"/>
                </StackPanel>

but put into a TabViewItem and the TextBoxRegex stops working:

<custom:TabView>
        <custom:TabView.Items>
            <custom:TabViewItem Header="Info">
                <StackPanel>
                    <TextBox Header="Nom" Text="{Binding Nom, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}"
                         extensions:TextBoxRegex.Regex="{x:Bind NomRegex}"
                         extensions:TextBoxRegex.ValidationMode="Forced" 
                         Background="{Binding (extensions:TextBoxRegex.IsValid), RelativeSource={RelativeSource Self}, Converter={StaticResource ValidationConverter}}"
                         Style="{StaticResource InputStyle}"/>
                    <Button Content="OK"/>
                </StackPanel>
            </custom:TabViewItem>
        </custom:TabView.Items>
    </custom:TabView>

with:

public class ValidationConverter : IValueConverter
    {
        public object Convert(object value, Type targetType, object parameter, string language) => (bool)value ? new SolidColorBrush(Colors.PaleGreen) : new SolidColorBrush(Colors.OrangeRed);
        public object ConvertBack(object value, Type targetType, object parameter, string language) => throw new NotImplementedException();
    }

private string NomRegex { get; } ="^.{2,}$";

[FrancoisM]

Note: the following does work as well so the issue is not with RelativeSource={RelativeSource Self}:

<custom:TabView>
        <custom:TabView.Items>
            <custom:TabViewItem Header="Info">
                <StackPanel>
                    <TextBox Header="Nom" Text="{Binding Nom, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}"
                             Background="{Binding Text, RelativeSource={RelativeSource Self}, Converter={StaticResource TestConverter}}"/>
                    <Button Content="OK"/>
                </StackPanel>
            </custom:TabViewItem>
        </custom:TabView.Items>
    </custom:TabView>

public class TestConverter : IValueConverter
    {
        public object Convert(object value, Type targetType, object parameter, string language) => ((string)value).Length >2 ? new SolidColorBrush(Colors.PaleGreen) : new SolidColorBrush(Colors.OrangeRed);
        public object ConvertBack(object value, Type targetType, object parameter, string language) => throw new NotImplementedException();
    }

[jeromelaban]

Thanks! On which platform do you see this behavior ?

[FrancoisM]

Sorry, forgot to mention it's on wasm.