I created a Goodnight & a GoodMorning button, to (as you might expect) turn on a bunch of lights in the morning, and turn off a bunch of lights at night respectively. All Leviton Z-Wave DZ6HD switches.
Sometimes when I 'push' the button it works, but more often than not, it only turns on/off a subset of lights. Seems to be a random subset.... if I hit the button again it usually catches all the ones it missed. I have the flag to only send the command to switches that are on/off. My Z-Wave mesh is quite healthy except for a couple of outliers - ironically the far away switches have never failed, it's ones that are close by the hub and have strong signals that usually are flakey.
It's almost like the hub just doesn't have the CPU horsepower to send out all the commands? I have a C7 version (ordered the C8 to see if it will help)