Upgrade to 0.84.x Breaks Light Switches in Frontend (Non-Lovelace)


After upgrading Hass.io to 0.84.x my light switches no longer show on the front end.
The entities still exist and work with automations etc and also showup on lovelace, but on the original front-end (using groups.yaml) they no longer show up (even though they are all still correctly configured both in configuration/lights.yaml and in groups.yaml)

I assume this is possibly related to the refactor of the mqtt light component - however I am using the default mode and there seems to be no breaking change to my config as below.
So under my lights.yaml I have …

          - platform: mqtt
            name: "Master Bedroom Lights"
            state_topic: "stat/masterbed_lights/POWER1"
            command_topic: "cmnd/masterbed_lights/POWER1"
            payload_on: "ON"
            payload_off: "OFF"
            qos: 0
            optimistic: false
            retain: true

Please can you help?

Thanks Cuan