Workaround for this issue is replacing the template for the RadWizard with:

    <ControlTemplate x:Key="RadWizardTemplate" TargetType="telerikNavigation:RadWizard">
        <Border Background="{TemplateBinding Background}" BorderBrush="{TemplateBinding BorderBrush}" BorderThickness="{TemplateBinding BorderThickness}">
              <Grid>
                <ContentPresenter x:Name="PART_SelectedPagePresenter" Content="{Binding SelectedPage, RelativeSource={RelativeSource TemplatedParent}}">
                    <ContentPresenter.Visibility>
                        <Binding RelativeSource="{RelativeSource TemplatedParent}" Path="IsContentPreserved" Converter="{StaticResource InvertedBooleanToVisibilityConverter}"/>
                    </ContentPresenter.Visibility>
                </ContentPresenter>
                <Grid x:Name="ContentElementsPanel" Visibility="{Binding RelativeSource={RelativeSource TemplatedParent}, Path=IsContentPreserved, Converter={StaticResource BooleanToVisibilityConverter}}"/>
            </Grid>
        </Border>
    </ControlTemplate>

instead of:

    <ControlTemplate x:Key="RadWizardTemplate" TargetType="telerikNavigation:RadWizard">
        <Border Background="{TemplateBinding Background}" BorderBrush="{TemplateBinding BorderBrush}" BorderThickness="{TemplateBinding BorderThickness}">
            <ContentPresenter x:Name="PART_SelectedPagePresenter" Content="{Binding SelectedPage,RelativeSource={RelativeSource TemplatedParent}}"/>
        </Border>
    </ControlTemplate>



Available in LIB version: 2017.2.605