RadioButtonOuterEllipseFill lightweight radio button style does not work

Describe the bug The lightweight style RadioButtonOuterEllipseFill (see documentation here) does not work. This was working before in UWP at some point.

Steps to reproduce the bug

 <RadioButton>
    <RadioButton.Resources>
           <ResourceDictionary>
                 <SolidColorBrush x:Key="RadioButtonOuterEllipseFill" Color="Red" />
                 <SolidColorBrush x:Key="RadioButtonOuterEllipseFillPointerOver" Color="Green" />
            </ResourceDictionary>
    </RadioButton.Resources>
</RadioButton>

RadioButton is filled white, and when hovered over changes to green, when it should be shown as a radiobutton filled in red that changes to green when pointer is over. Observe that RadioButtonOuterEllipseFill is not applied at all.

Version Info

NuGet package version:
WinUI 3 - Project Reunion 0.5: 0.5.5

Windows app type:

UWP	Win32
	Yes

Windows 10 version	Saw the problem?
Insider Build (xxxxx)
October 2020 Update (19042)	Yes
May 2020 Update (19041)
November 2019 Update (18363)
May 2019 Update (18362)
October 2018 Update (17763)
April 2018 Update (17134)
Fall Creators Update (16299)
Creators Update (15063)

Device form factor	Saw the problem?
Desktop	Yes
Xbox
Surface Hub
IoT

Additional context While I am not super familar with how WinUI works behind the scenes, I would guess that this line should also be a ThemeResource instead of a StaticResource.

[karkarl]

Additionally, this visual state group is the default state and should not have any setters:

https://github.com/microsoft/microsoft-ui-xaml/blob/2c1d7144a0c5ffe4fae25f0be2fdaf40bd41973c/dev/CommonStyles/RadioButton_themeresources.xaml#L220

The setters for the CommonStates were necessary for the colour animations to animate back to the correct colour. It seems when the colour animation bindings were updated they weren’t removed, let me investigate and will remove them if necessary.

I would guess that this line should also be a ThemeResource instead of a StaticResource.

I can send a fix out for that as well.

[chingucoding]

@karenbtlai Do you have any updates on this? ^^