I'm an IT tech for a small computershop and i've noticed this problem on nearly every windows 10 PC on which the user is running Voip Connect. As does AlanD1948.
I've searched and spend a lot of time trying to find a work around without having to tell my client to simply force shutdown or right click the voip connect tray icon to close the application before shutdown and came to this thread so i thought i'd mention it.
I can't determine if the cause is a windows 10 version or a Voip Connect build because i simply dont have the time to try it out. But maybe it helps someone here or from MS even to find a solution.
Kind Regards