I am having the same problem as described in Yeelight JIAOYUE YLXD02YL 650 Surrounding Ambient Lighting LED Ceiling Light disappeared and some other posts.
I turned on the Yeelight galaxy lamp but no ambient led lights were turned on.
I tried going to the app which had some problems connecting and after it connected, I have tried to control the lamp, when turning the main light on and off through the app, everything works, when i moved to the ambient part, turning it on and off doesnt affect the lamp, but it does affect the app animation as if it worked. (ambient is always off on the lamp itself).
I would like to mention that I have more then 20 of your devices in my parents and my house, and was really recommending everyone to purchase them.
But now the most expansive lamp, of which I purchased 2 for myself and 2 for my parents, stopped working properly after few month.
My two lamps are side by side in the living room, so if the backlight doesn’t work for one I have to disable it for the other or it will look weird.
I don’t know if it relates to the issues, but the same lamp was randomly resetting when it was on, until I updated it - then it was working well until the backlight issue.
I work in a tech company that works with electronics, and I hope you can advice me how can I fix the issue. I can solder or replace a part by myself if it isnt too complicated.