There is a crash in the new code that have been added to 3.2.1 when stopping PIE (returned Viewport pointer is nullptr):

    UGameViewportClient* ViewportClient = GetWorld()->GetGameViewport();
    FSceneViewport* Viewport = ViewportClient->GetGameViewport();

 auto ViewportPosition = Viewport->GetInitialPositionXY();

auto ViewportSize = Viewport->GetSizeXY();
auto UnscaledViewRect = FIntRect(ViewportPosition.X, ViewportPosition.Y, ViewportPosition.X + ViewportSize.X, ViewportPosition.Y + ViewportSize.Y);
NoesisSlateElement->ViewLeft = UnscaledViewRect.Min.X;
NoesisSlateElement->ViewTop = UnscaledViewRect.Min.Y;
NoesisSlateElement->ViewRight = UnscaledViewRect.Max.X;
NoesisSlateElement->ViewBottom = UnscaledViewRect.Max.Y;