I can't figure out why my Label isn't triggering the converter when inside of span, but does when it isn't? What am I missing here?

I have two Label examples for the same data. One works - but doesn't work like I want it to (it colorized all of the text based on the community name rather than both the community name and the username being different colors), the other works - but doesn't trigger the converter to fire (so the text displays as expected, but doesn't run through the converter for colorization). I think the second one that doesn't trigger the convertor is what I'm after.

Working Label, but doesn't do what I want

<Label 
    x:Name="communityAndUserLabel"
    Grid.Row="2"
    Grid.Column="1"
    FontAttributes="None"
    VerticalOptions="End">
    <Label.Text>
        <MultiBinding StringFormat="{}{0} • {1}" Mode="TwoWay">
            <Binding Path="CommunityName" />
            <Binding Path="Username" />
        </MultiBinding>
    </Label.Text>
    <Label.TextColor>
        <MultiBinding Converter="{StaticResource nameColorMulti}" ConverterParameter="community">
            <Binding Path="CommunityName" />
            <Binding Path="Username" />
        </MultiBinding>
    </Label.TextColor>
</Label>

Label that won't trigger the converter, but still shows the text

<Label 
    x:Name="communityAndUserLabel"
    Grid.Row="2"
    Grid.Column="1"
    FontAttributes="None"
    VerticalOptions="End">
    <Label.FormattedText>
        <FormattedString>
            <Span Text="{Binding CommunityName, Mode=TwoWay}" TextColor="{Binding CommunityName, Converter={StaticResource nameColorMulti}, ConverterParameter=community}" />
            <Span Text=" • " TextColor="Gray" />
            <Span Text="{Binding Username, Mode=TwoWay}" TextColor="{Binding Username, Converter={StaticResource nameColorMulti}, ConverterParameter=username}" />
        </FormattedString>
    </Label.FormattedText>
</Label>

Any idea on what I'm overlooking here on why the second one doesn't trigger the converter?

• View
• ViewModel
• Converter
• App.xaml

It dawned on me this morning that since I had separated the text out in the xaml I no longer needed to use a IMultiValueConverter - so instead I created two separate IValueConverters to get this done:

<Label 
    x:Name="communityAndUserLabel"
    Grid.Row="2"
    Grid.Column="1"
    FontAttributes="None"
    VerticalOptions="End">
    <Label.FormattedText>
        <FormattedString>
            <!-- Use Binding markup extensions with Converter attributes -->
            <Span Text="{Binding CommunityName}" TextColor="{Binding CommunityName, Converter={StaticResource communityNameColor}}" />
            <Span Text=" • " TextColor="Grey" />
            <Span Text="{Binding Username}" TextColor="{Binding Username, Converter={StaticResource usernameColor}}" />
        </FormattedString>
    </Label.FormattedText>
</Label>