The current workaround we can offer is to define the following style for the RadioButton element:
<Style TargetType="RadioButton" BasedOn="{StaticResource RadioButtonStyle}">
<Style.Triggers>
<Trigger Property="IsChecked" Value="True">
<Setter Property="BorderBrush" Value="{telerik1:FluentResource ResourceKey=AccentBrush}" />
</Trigger>
</Style.Triggers>
</Style>
Where
xmlns:telerik1="clr-namespace:Telerik.Windows.Controls;assembly=Telerik.Windows.Controls"
Hi, The fix will be available in our next official version – R2 2018, scheduled for the middle of May. Best regards, Ralitsa Kumanova