MainWindow.xaml

<Window x:Class="XamlToolkitBindingIssue.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:local="clr-namespace:XamlToolkitBindingIssue"
        xmlns:materialDesign="http://materialdesigninxaml.net/winfx/xaml/themes"
        mc:Ignorable="d"
        Title="MainWindow" Height="350" Width="525">
    
    <Window.DataContext>
        <local:MainWindowsViewModel/>
    </Window.DataContext>
    
    <materialDesign:DialogHost Identifier="RootDialog">
        <StackPanel
            
            Orientation="Vertical"
            Margin="5px, 10px">

            <TextBlock Text="Hello"/>
            <Rectangle 
                Margin="0 20px"
                Height="1px"
                Fill="LightGray" />
            
            <ContentControl 
                Content="{Binding CurrentView}"
                Height="Auto"
            />

        </StackPanel>
    </materialDesign:DialogHost>
</Window>