SplitView Pane not shown

[void22]

Describe the bug
When SplitView initialized with _split.Visibility=Visibility.Collapsed then later changed to _split.Visibility=Visibility.Visible Pane does not appear.

To Reproduce

MainWindow.xaml

<controls:MetroWindow x:Class="guitest.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
        xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
        xmlns:controls="clr-namespace:MahApps.Metro.Controls;assembly=MahApps.Metro"
        xmlns:local="clr-namespace:guitest"
        mc:Ignorable="d"
        Title="MainWindow" Height="450" Width="800">
    
    <Grid>
        <StackPanel x:Name="_stack">
            <Button Content="to SpliView" Width="95" Height="35" Click="Button_Click" />
        </StackPanel>
        <controls:SplitView x:Name="_split" Background="Green" DisplayMode="Inline" CompactPaneLength="60" OpenPaneLength="250" PaneBackground="Red" IsPaneOpen="True">
            <Button Content="to TabControl" Width="95" Height="35" Click="Button_Click_1" />
        </controls:SplitView>
    </Grid>
</controls:MetroWindow>

MainWindow.xaml.cs

public partial class MainWindow : MetroWindow
{
    public MainWindow()
    {
        InitializeComponent();

        _split.Visibility = Visibility.Collapsed;
        _stack.Visibility = Visibility.Visible;
    }

    private void Button_Click(object sender, RoutedEventArgs e)
    {
        _split.Visibility = Visibility.Visible;
        _stack.Visibility = Visibility.Collapsed;
    }

    private void Button_Click_1(object sender, RoutedEventArgs e)
    {
        _split.Visibility = Visibility.Collapsed;
        _stack.Visibility = Visibility.Visible;
    }
}

If the SplitView set to visible first, everything is working as expected.

public MainWindow()
{
    InitializeComponent();

    _split.Visibility = Visibility.Visible;
    _stack.Visibility = Visibility.Collapsed;
}

Expected behavior
SplitView.Pane displayed with size specified in OpenPaneLength.

Screenshots
Expected output:

Wrong output:

Environment:

• MahApps.Metro v1.6.5 from NuGet
• OS: Win10 1903
• Visual Studio 2017 15.9.13
• .NET Framework 4.7.1

Additional context
2.0.0-alpha0391 (from NuGet) also not working properly. Maybe Windows 1903 update causes the problem.

[punker76]

@void22 this has now been fixed, and it will be released in the next version of MahApps.Metro v2.0