Thanks Ryan, yep I understand ZLL vs. ZHA. I read that the v3 ST hub was certified for version 3.0 Zigbee devices. Yet you say there is no v3 of Zigbee. My new switch today is a “Wireless Protocol ZigBee 3.0”. Its working good now.
Theres actually quite a few articles on Zigbee 3.0. https://www.zigbee.org/zigbee-for-developers/zigbee-3-0/. Samsung was one of the first eight companies to receive Zigbee 3 certification in 2016. https://community.smartthings.com/t/samsung-receives-zigbee-3-0-certification/66882
Here is an article that talks about ZigBee 3 with SmartThings 3. https://community.smartthings.com/t/samsung-smartthings-hub-2018-discussion-model-gp-u999sjvlgda-aka-v3/133335/82
Thanks for your assistance Ryan, I am all hooked up now and everything is working great.
Dave