For reference to setup UWP references: https://docs.microsoft.com/en-us/windows/apps/desktop/modernize/desktop-to-uwp-enhance
C:\Program Files (x86)\Windows Kits\10\UnionMetadata\10.0.18362.0\Facade\windows.winmd C:\Program Files (x86)\Windows Kits\10\References\10.0.18362.0\Windows.Foundation.UniversalApiContract\8.0.0.0\Windows.Foundation.UniversalApiContract.winmd C:\Program Files (x86)\Windows Kits\10\References\10.0.18362.0\Windows.Foundation.FoundationContract\3.0.0.0\Windows.Foundation.FoundationContract.winmd
Make sure to set copy local to false for all UWP references
DesktopToast\ToastManager.cs @ private static async Task ShowBaseAsync(XmlDocument document, string appId) // Create a timeout to prevent history piling up toast.ExpirationTime = DateTimeOffset.Now.AddSeconds(30);