When a Hue bulb has been powered down and then up again it starts up at full brightness and white color. However in the logs it mostly does not get updated and still shows brightness and on/off state and color prior to the power down.
When using the Hue Bridge the light status gets updated within seconds.
Can someone agree to this behaviour?. Maybe even have an explanation or solution.
Do you have the report function enabled? This is required if you wan’t to get state changes which are not caused by zigbee2mqtt. https://www.zigbee2mqtt.io/information/report.html
I just tried to enable the report function but no change. When powering Down a hue bulb no updated values are shown in the logs after powering it up again.
In HA nothing is updated too.
I was mistaken, you should use the availability_timeout (https://www.zigbee2mqtt.io/configuration/configuration.html)
Si I should not have “report: true” but only “availability_timeout: 0” in the config?
Not availability_timeout: 0 as it will never check the availability then, availability_timeout: 30 should be a good value (but you can also try reducing it), the lower the more stress on the network you will get.
With 30 it will check the availability of device every 30 seconds.
yes of course 
Now it show the correct on/off state and brightness after the chosen time, but the color stays the same prior to the powerdown.
Should be fixed in the latest dev branch.
I finally got to test this and it works fine now 
Anyway I notice that when changing from a color in HomeAssistant to a Kelvin degree the color feedback does not change. It still shows the color choosen before changing to Kelvin.