MQTT climate doesn't work correctly with Google Assistant

[joshtbernstein]

Home Assistant release with the issue:

0.82

Last working Home Assistant release (if known):

Operating environment (Hass.io/Docker/Windows/etc.):

Hass.io on Docker on CentOS 7

Component/platform:

https://www.home-assistant.io/components/climate.mqtt/

Description of problem:
In Google Assistant, the entity shows the current temperature, but shows "Loading" for the target temperature. I'm unable to open the modes menu or adjust the target temperature.

Problem-relevant configuration.yaml entries and (fill out even if it seems unimportant):

climate:
  - platform: mqtt
    name: Thermostat
    modes:
      - "Off"
      - "Heat"
      - "Cool"
    fan_modes:
      - "Auto"
      - "On"
    current_temperature_topic: "hvac/current_temperature/get"
    mode_command_topic: "hvac/mode/set"
    mode_state_topic: "hvac/mode/get"
    temperature_command_topic: "hvac/temperature/set"
    temperature_state_topic: "hvac/temperature/get"
    fan_mode_command_topic: "hvac/fan/set"
    fan_mode_state_topic: "hvac/fan/get"
    min_temp: 45
    max_temp: 95

cloud:
  google_actions:
    filter:
      exclude_entities:
        - light.bedroom
        - light.office

Traceback (if applicable):

Additional information:

[joshtbernstein]

HomeKit issues could be something else. Removing.

[joshtbernstein]

Turned on debugging and it looks like HA isn't sending Google the current setpoint or mode:

climate.thermostat': {
  'online': True,
  'thermostatTemperatureAmbient': 21.7
}

Compared to what is sent for a zwave thermostat:

climate.2gig_technologies_ct101_thermostat_iris_cooling_1': {'
  online': True,
  'thermostatMode': 'cool',
  'thermostatTemperatureAmbient': 21.7,
  'thermostatTemperatureSetpoint': 23.3
}

[joshtbernstein]

Part of the issue seems to be with capitalizing the modes. If I change my config to the following, I can see and adjust the target setpoint from Google. However, I still can't view or change the mode.

climate:
  - platform: mqtt
    name: Thermostat
    modes:
      - "off"
      - "heat"
      - "cool"
    fan_modes:
      - "Auto"
      - "On"
    current_temperature_topic: "hvac/current_temperature/get"
    mode_command_topic: "hvac/mode/set"
    mode_state_topic: "hvac/mode/get"
    temperature_command_topic: "hvac/temperature/set"
    temperature_state_topic: "hvac/temperature/get"
    fan_mode_command_topic: "hvac/fan/set"
    fan_mode_state_topic: "hvac/fan/get"
    min_temp: 45
    max_temp: 95

[joshtbernstein]

The mode select started working the other day, not sure why.

[cgarwood]

Closing in favor of #18645