Thanks for the information your post provides. I created a override for my melinera christmas string the following way:
homeassistant:
customize:
...
light.color_dimmable_light_19:
effect_list:
- steady
- snow
- rainbow
- snake
- twinkle
- firework
- horizontal_flag
- waves
- updown
- vintage
- fading
- collide
- strobe
- sparkles
- carnaval
- glow
it’s showing up fine in web ui, but does not work. Will try with your api call… What api endpoint you are sending the calls to? phoscon or homeassistant?