Issue still remains, and my quick work around for now is to use the Screen Connect app. In there you can send keyboard commands, just select the "WIN" then Q to, and it will quit whatever app is running and not your phone.
Not a quick or easy work around, but since the "Windows" key maps cleanly to the client machine "Command" key it seems to be the easiest way right now.
Totally on board that once in a session, command keys should route to that session and not the host machine.
Customer support service by UserEcho