I don't have a G2, but I know what you mean about the Quiet mode not quite working properly. I finally gave in and got an app. Nights Keeper on Play. Free and it works; even on Android L.
I haven't had any issues with it. It starts and stops on schedule. Do you have the notification icon on the top? It looks like a 1/4 moon with a clock.
I've had issues since day 1... With both versions of Android. In my case quiet mode turns off at 01:00 regardless of any schedule. I gave up on using it. Couldn't find a fix, and even a reset didn't help.