This hang occured for us also, sdk also started allocating huge amounts of memory during the hang, we are using version 100.12.
callstack:
[Managed to Native Transition]
> Esri.ArcGISRuntime.WPF.dll!RuntimeCoreNet.CoreDxDevice.Pause(RuntimeCoreNet.GeneratedWrappers.CoreGraphicsHardwareResources resources) Unknown
Esri.ArcGISRuntime.WPF.dll!Esri.ArcGISRuntime.UI.Controls.GeoView.StopRendering() Unknown
Esri.ArcGISRuntime.WPF.dll!Esri.ArcGISRuntime.UI.Controls.GeoView.OnUnloadedAsync() Unknown
Esri.ArcGISRuntime.WPF.dll!Esri.ArcGISRuntime.UI.Controls.GeoView.MapSurfaceElement_Unloaded(object sender, System.Windows.RoutedEventArgs e) Unknown
PresentationCore.dll!System.Windows.EventRoute.InvokeHandlersImpl(object source, System.Windows.RoutedEventArgs args, bool reRaised) Unknown
PresentationCore.dll!System.Windows.UIElement.RaiseEventImpl(System.Windows.DependencyObject sender, System.Windows.RoutedEventArgs args) Unknown
PresentationFramework.dll!System.Windows.BroadcastEventHelper.BroadcastEvent(System.Windows.DependencyObject root, System.Windows.RoutedEvent routedEvent) Unknown
PresentationFramework.dll!System.Windows.BroadcastEventHelper.BroadcastUnloadedEvent(object root) Unknown
PresentationCore.dll!MS.Internal.LoadedOrUnloadedOperation.DoWork() Unknown
PresentationCore.dll!System.Windows.Media.MediaContext.FireLoadedPendingCallbacks() Unknown
PresentationCore.dll!System.Windows.Media.MediaContext.FireInvokeOnRenderCallbacks() Unknown
PresentationCore.dll!System.Windows.Media.MediaContext.RenderMessageHandlerCore(object resizedCompositionTarget) Unknown
PresentationCore.dll!System.Windows.Media.MediaContext.AnimatedRenderMessageHandler(object resizedCompositionTarget) Unknown
WindowsBase.dll!System.Windows.Threading.ExceptionWrapper.InternalRealCall(System.Delegate callback, object args, int numArgs) Unknown
WindowsBase.dll!System.Windows.Threading.ExceptionWrapper.TryCatchWhen(object source, System.Delegate callback, object args, int numArgs, System.Delegate catchHandler) Unknown
WindowsBase.dll!System.Windows.Threading.DispatcherOperation.InvokeImpl() Unknown
WindowsBase.dll!MS.Internal.CulturePreservingExecutionContext.CallbackWrapper(object obj) Unknown
mscorlib.dll!System.Threading.ExecutionContext.RunInternal(System.Threading.ExecutionContext executionContext, System.Threading.ContextCallback callback, object state, bool preserveSyncCtx) Unknown
mscorlib.dll!System.Threading.ExecutionContext.Run(System.Threading.ExecutionContext executionContext, System.Threading.ContextCallback callback, object state, bool preserveSyncCtx) Unknown
mscorlib.dll!System.Threading.ExecutionContext.Run(System.Threading.ExecutionContext executionContext, System.Threading.ContextCallback callback, object state) Unknown
WindowsBase.dll!MS.Internal.CulturePreservingExecutionContext.Run(MS.Internal.CulturePreservingExecutionContext executionContext, System.Threading.ContextCallback callback, object state) Unknown
WindowsBase.dll!System.Windows.Threading.DispatcherOperation.Invoke() Unknown
WindowsBase.dll!System.Windows.Threading.Dispatcher.ProcessQueue() Unknown
WindowsBase.dll!System.Windows.Threading.Dispatcher.WndProcHook(System.IntPtr hwnd, int msg, System.IntPtr wParam, System.IntPtr lParam, ref bool handled) Unknown
WindowsBase.dll!MS.Win32.HwndWrapper.WndProc(System.IntPtr hwnd, int msg, System.IntPtr wParam, System.IntPtr lParam, ref bool handled) Unknown
WindowsBase.dll!MS.Win32.HwndSubclass.DispatcherCallbackOperation(object o) Unknown
WindowsBase.dll!System.Windows.Threading.ExceptionWrapper.InternalRealCall(System.Delegate callback, object args, int numArgs) Unknown
WindowsBase.dll!System.Windows.Threading.ExceptionWrapper.TryCatchWhen(object source, System.Delegate callback, object args, int numArgs, System.Delegate catchHandler) Unknown
WindowsBase.dll!System.Windows.Threading.Dispatcher.LegacyInvokeImpl(System.Windows.Threading.DispatcherPriority priority, System.TimeSpan timeout, System.Delegate method, object args, int numArgs) Unknown
WindowsBase.dll!MS.Win32.HwndSubclass.SubclassWndProc(System.IntPtr hwnd, int msg, System.IntPtr wParam, System.IntPtr lParam) Unknown
[Native to Managed Transition]
[Managed to Native Transition]
WindowsBase.dll!System.Windows.Threading.Dispatcher.PushFrameImpl(System.Windows.Threading.DispatcherFrame frame) Unknown
PresentationFramework.dll!System.Windows.Application.RunDispatcher(object ignore) Unknown
PresentationFramework.dll!System.Windows.Application.RunInternal(System.Windows.Window window) Unknown