Control of item not possible


I’m using openhabian on my raspberry pi and bought a zigbee gateway to control zigbee devices.
I’ve added the zigbee gateway (POPP Zigbee Stick) and a Ledvance LED lamp (Classic E27 Multicolor) as things and created new items which I linked to the channels. One channel of the lamp is for regulating the light temperature, another one for controlling the color and switching on and off. For the light temperature, there’s a slider which works fine. For the light color however, there is no slider or anything else to control the color or switch on and off. The status of the item is NULL.
Am I missing something?
Any help is appreciated!

Sound familiar, I have a popp stick and several zigbee devices as well. When the item shows null (usually after adding it) the gui on the item disappeared. For me changing configuration of the (derived) color thing/channels to “follow” and turning it on with the switch item made the color working.

After switching the device on and off several times, it suddenly worked. If the problem appears again, I will try to change the configuration as you explained.