System.NotSupportedException
  HResult=0x80131515
  Message=Unrecognized short identifier 'StackMode'; Define type and parameters of property in first occurrence in InAppNotificationXaml.bind.
  Source=Microsoft.Toolkit.Uwp.SampleApp
  StackTrace:
   at Microsoft.Toolkit.Uwp.SampleApp.Sample.<PreparePropertyDescriptorAsync>d__91.MoveNext() in C:\Users\Rosario\source\repos\WindowsCommunityToolkit\Microsoft.Toolkit.Uwp.SampleApp\Models\Sample.cs:line 466
   at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
   at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at System.Runtime.CompilerServices.TaskAwaiter.GetResult()
   at Microsoft.Toolkit.Uwp.SampleApp.SampleController.<OnNavigatedTo>d__14.MoveNext() in C:\Users\Rosario\source\repos\WindowsCommunityToolkit\Microsoft.Toolkit.Uwp.SampleApp\Pages\SampleController.xaml.cs:line 232

  This exception was originally thrown at this call stack:
    Microsoft.Toolkit.Uwp.SampleApp.Sample.PreparePropertyDescriptorAsync() in Sample.cs
    [External Code]
    Microsoft.Toolkit.Uwp.SampleApp.SampleController.OnNavigatedTo(Windows.UI.Xaml.Navigation.NavigationEventArgs) in SampleController.xaml.cs

NuGet Package(s): 

Package Version(s): 

Windows 10 Build Number:
- [ ] Fall Creators Update (16299)
- [ ] April 2018 Update (17134)
- [ ] October 2018 Update (17763)
- [ ] May 2019 Update (18362)
- [ ] May 2020 Update (19041)
- [ ] Insider Build (build number: )

App min and target version:
- [ ] Fall Creators Update (16299)
- [ ] April 2018 Update (17134)
- [ ] October 2018 Update (17763)
- [ ] May 2019 Update (18362)
- [ ] May 2020 Update (19041)
- [ ] Insider Build (xxxxx)

Device form factor:
- [ ] Desktop
- [ ] Xbox
- [ ] Surface Hub
- [ ] IoT

Visual Studio 
- [ ] 2017 (version: )
- [ ] 2019 (version: ) 
- [ ] 2019 Preview (version: )