On my g4,it works with the qc case setting set to offIt appears to be tied to the Quick Circle Case toggle in settings. When it turned that toggle off, this stopped working.
What I like about it is that you can do a lot less "waking the screen" in order to check the time. Double tapping is great, and I use it all the time, but a) it turns the whole screen on which in bright light is a battery waster, and b) you then have to re-sleep the screen when you're done.