Actually my led strip don’t have warm and cold white so i can’t test, but i guess you should use a dimmer instead of a switch.
For the stateTopic you should also use the transformationPattern
transformationPattern: REGEX:(.*\"White\".*)∩JSONPATH:$.White
okay, finally I have an idea why you did not get this message: I think it requires the command SetOption4 1 in the Tasmota Webconsole.
Apparently I routinely issue this command on any new Tasmota device, although I don’t remember it 
Form Tasmota documentation:
SetOption4:
Return MQTT response as
0 = RESULT topic (default)
1 = %COMMAND% topic
This allows to use individual state topics for all openHAB channels and makes the chained state transformation with the Regex unnecessary. Sorry I didn’t remember this until now. It answers your original question of “why does the item linked to the HSBCOLOR channel not change”.
The solution of chaining state transformations has the advantage of not having to set this non-default setting on every Tasmota device (and then forgetting about it), so it’s probably a better solution overall.
Thank you so much! This was missing on the sites I looked at.
I’ll keep it that way with reggex
I’m currently setting Alexa up.
I created a group (g_Schreibtisch) for Brightness, Color HSB and Power.
This works fine. Everything can be controlled as one item (added Alexa Metadata).
Since I don’t think RGB + W works with Alexa, I tried splitting it up:
one more group, g_SchreibtischWeiss which includes the White Element and also the Dimmer.
But there I can’t setup the deployed items in the Meta Data
VS
Do you have an idea or is there a more elegant solution?
What I want to control is
“Alexa turn Schreibtisch warmwhite an” or similar (not the artifical cold white which works right now)
In case of a Color Light i would stick to to the default SetOption4 0
because if your light is off and you change any channel, color, dimmer or white, the light will be swiched on and also the power state changes but it’s only published in
stat/........../HSBCOLOR
stat/........../Dimmer
stat/........./White
but not in
stat/........../POWER
So in OH the light switch stay off but the light is actually on!
I would activate the Hue Emulation in Tasmota and connect the lamp directly to alexa.
That was my first guess too.
I didn’t like it, its a bit unreliable with THIS network setup.
MQTT and then cloud binding works stable.
And also its bundled.
Okay, found the problem.
The items need the metadata even if its set for the group.
For white it can be set as toggle state and there’s one more option in the Alexa light.
Now I can say turn Schreibtisch warmweiss an.
Schreibtisch is the normal item, and warmweiss is the subitem which gets toggled.
Maybe this helps other people