A long time ago I set up a group, device, and a button to turn on some lights. I went back to look at this (in reference to the new Room Lighting app) but for the life of me, I can't figure out what I did and why it works.
I created a group that defines a couple of lights:
This may be a dumb newbie question, but I don't see how the device knows to run the specific group as I see no link in the device data that indicates which group to run.
As a second question: Does the new Room Lighting App support metering? I need that for reliable automations and the reason why I am using a group instead of just a rule.
I see that the device type for your virtual dimmer dev_test is Group Dimmer...
I think it's likely this is the auto-created device associated with the group, which you may have renamed. The App listens for events from this device, then sends the same commands to the selected members.
No a few versions back and with the z-wave firmware update (z-wave settings page) the staff said there should be no longer a requirement for metering the commands and the hub handles it now. I removed all of mine at the time and it did indeed no longer require it on mine.
This is where you tripped. There is no need for this, the app created one for you which is linked. (Same thing happens on Room lighting) that's the device which you need to control.
