Mqtt_template not showing brightness slider


i’m trying to implement the mqtt_template light entity but stumble upon some problems.
First not a really big problem:
When i change the color my led strip changes color the right callback is done but the icon in the interface doesn’t change until i reload the webpage.
Second: when i click on the light there isn’t a slider for the brightness. If i change the css in chrome so i can see the slider and use it, it works, but it won’t show.

If i check in developer tools states i see that the light doesn’t have any supported_features is that normal?
my configuration is like this:

- platform: mqtt_template
  name: "Kast LEDs2"
    - Rainbow
    - Solid
  command_topic: "hass/secondstrip/setpower"
  state_topic: "hass/secondstrip/setpowerpub"
  command_on_template: >
    {"state": "on"
    {%- if brightness is defined -%}
    , "brightness": {{ brightness }}
    {%- endif -%}
    {%- if red is defined and green is defined and blue is defined -%}
    , "color": [{{ red }}, {{ green }}, {{ blue }}]
    {%- endif -%}
    {%- if effect is defined -%}
    , "effect": "{{ effect }}"
    {%- endif -%}
  command_off_template: '{"state": "off"}'
  state_template: '{{ value_json.state }}'
  brightness_template: '{{ value_json.brightness }}'
  red_template: '{{ value_json.color[0] }}'
  green_template: '{{ value_json.color[1] }}'
  blue_template: '{{ value_json.color[2] }}'
  effect_template: '{{ value_json.effect }}'

Nobody has tried to use the mqtt_template?

I have the same problem.

okey than i’m going to make issue on github
i’ve made following issue #5714