I just got 3 Yeelight LED white bulbs yesterday (October 30). When I first installed them using the Yee app (USA server) and linked to my Alexa account I could ask Alexa to set the colour temperature (“Alexa make the light daylight” or “Alexa, make the light warm white”, etc.). They worked perfectly.
Then I updated the firmware and now the only thing Alexa can do is turn the lights on/off or dim the output level. If I ask Alexa to change the colour temperature the response is “that only works when the lights are set to a shade of white”.