core: MQTT entities not supported by Statistics Graph Card

The problem

I tried to use the new Statistics Graph Card with my MQTT sensors but the entities don’t show up. According to the documentation this might be because of a bug. The same documentation advices me to contact the developer to point out this bug. Now I know the MQTT plugin is written by the HA team so I feel a bit like an unintentional smart-ass pointing this out but didn’t see any other bug report and didn’t find anything on the documentation.

Snippet of configuration.yaml file with the specific sensor

  - platform: mqtt
    name: "huis_84cca82cd610_co2"
    state_topic: "/huis/84cca82cd610/sensor/mhz19"
    unit_of_measurement: "ppm"
    value_template: "{{ value_json.co2 }}"

What is version of Home Assistant Core has the issue?

2021.8.8

What was the last working version of Home Assistant Core?

No response

What type of installation are you running?

Home Assistant OS

Integration causing the issue

mqtt

Link to integration documentation on our website

https://www.home-assistant.io/integrations/mqtt

Example YAML snippet

- platform: mqtt
    name: "huis_84cca82cd610_co2"
    state_topic: "/huis/84cca82cd610/sensor/mhz19"
    unit_of_measurement: "ppm"
    value_template: "{{ value_json.co2 }}"

Anything in the logs that might be useful for us?