In a WPF desktop application using Microsoft.Windows.SDK.Contracts (version 10.0.22621.755) I simply call the following code while debugging in Visual Studio.
SmartCardReader scr = await SmartCardReader.FromIdAsync(@"the_Device_ID");
When I shutdown the application by closing the WPF window, Visual studio takes 10 to 15 seconds to stop running. Is this to be expected or am I not cleaning up something I should in Windows.Devices.SmartCards