Comment 89 for bug 1568604

@unrud: Your hunch was right. Increasing the delay (even to 2 seconds is enough) resolves the issue. Even on your fresh installation, do check if it works correctly with suspend/hibernate as well when the delay is not more than one second.

I have gone back to gnome-screensaver for the time being, however, because my Wi-Fi keeps going off after resuming from more than one consecutive (with no intervening normal reboot) suspend/hibernate states with light-locker (I don't know why).