Can't reliably control Zigbee lights individually, control via lighting group works every time

Hi all-

First post, and fairly new to HA so please forgive me if I’m not doing this quite right.

I have a SmartThings v2 hub with several devices connected and generally working well- a few smart outlets, temp/humidity sensors, smart lights, smart switch.

I purchased and installed 7 of these Sylvania/Osram Zigbee under cabinet lights (of various lengths): (example)

They look great, and at one point or another I have been able to get each of them to pair and communicate with the controller properly and use the SmartThings app to adjust the brightness and color temp.

I have created a scene where all the lights are turned on and set to specific brightness/color temp, but I can’t get it to work properly. When I trigger it, it ends up controlling some of the lights, but not all of them, even though all of the lights are added to the scene. Also, when I try to control the problem lights individually via the ST app, they do not respond, even though they show online. Also, it is not always the same lights that are a problem. The problem seems to move around- one day it’s a light by the stove that’s not working, the next time after fiddling them them for a while it’s a light by the sink that’s not working and the one by the stove starts working. So I think they all are functional lights, but there seems to be some kind of communication problem.

To make things even more interesting, what I have noticed is that ALL of the lights DO reliably respond to ST app commands via a ST Lighting Group. I can power them all on/off, and set the dimmer level via the lighting group and ALL of the 7 lights respond quickly and flawlessly.

So why can’t I control some of them individually? And why can’t I get them to work in a scene?



PS, I have removed the all the undercabinet lights and re-added them to the ST hub several times over the past week or two, and also have tried to get my zigbee network to rebuild by powering off the hub (including removing batteries) for 30 minutes and then powering back on. This did not resolve the issue.