Can't get "cover" device_class: garage to work

Configuration
1

I built this garage-door opener following instructions provided by Dr.Z in this video:

Everything works except for the User Interface. By defining a “cover”, and specifying a device_class of “garage”, I was expecting to see a garage icon along with two up-down-arrow indicators that reflects the status of a reed switch, and double as buttons I can click to open and close the garage door. Instead, all I see is an icon of a garage.

I have this in my configuration.yaml file:

cover:
  - platform: mqtt
    name: "Center Garage Door" 
    state_topic: "cmnd/centerGarageDoorState/POWER2" 
    command_topic: "cmnd/centerGarageDoor/POWER1" 
    payload_open: "ON" 
    payload_close: "ON"
    payload_stop: "ON" 
    state_open: "ON" 
    state_closed: "OFF" 
    optimistic: false

And this in my customize.yaml file:

cover.center_garage_door:
  device_class: garage
  friendly_name: "Middle Garage Door"

What am I doing wrong?

2

To make everything show properly in the Overview, I had to manually add the covers by editing the UI.

I thought by putting the “cover” entities in a Group. The Group and associated entities would show up in the UI upon HA restart. Is this not the case?