This is a small but common annoyance which appears to be fully reproducible and should be an easy fix. When I choose to shut down or restart Windows 10, and the Lightroom CC app is running, then it prevents the restart or shutdown from happening unless I explicitly go into Lightroom and exit the application, first. It's the only application on my system that does this. I'm not even editing any photo or in the middle of any other change. I just have an album showing. It's still happening on the latest build 2.2 released just now.