Helper entity for Temperature not in Area configuration

I have just integrated a Zigbee thermostat using Z2M. It shows up as a climate sensor and works fine, however it reports the temperature as an attribute which is not selectable in the area configuration.
I created a helper entity with the respective template and assigned it to the area, but it still does not show up in the area configuration as a temperature sensor.

What am I missing here?

Kind regards,
blindcoder

Same issue I have noticed. I have helpers template and max/min and none of them show up as pickable in the area config. I suspect - it will only show temperature sensors attached to a device.

What do you see in Developer’s Tools, States?

sensor.average_garden_temperature

Helper - combine the state of several sensors.

state_class: measurement
unit_of_measurement: °C
icon: mdi:forest-outline
friendly_name: Average Garden Temperature

No device_class added to the sensor.

sensor.tmpl_outside_temeprature

This is a template sensor with the device_class added.

state_class: measurement
unit_of_measurement: °C
device_class: temperature
friendly_name: TMPL Outside Temperature

This DOES show up in the area config.

The problem is obviously that the helper sensor should be inheriting the device_class of the first available sensor in the group.