Template entity showing as "Unknown", but it is in History

I have a template sensor for weight (that automatically distinguishes between two persons by approximate weight).

Problem is, the value just disappears (shows “Unknown”) after a period of time, and after HA restarts. It IS included in History and Logbook portions of congifuration.yaml, and it DOES show in History.

I want it to stay and show the last known value in a Lovelace badge.

This is the sensor:

  - platform: template
    sensors:
      weight_name_jiri:
        friendly_name: "Weight Jiri"
        value_template: >-
          {% set weight = states('sensor.ble_miscale_weight') | float %}
            {% if 80 <= weight <= 100 %}
              {{ states("sensor.ble_miscale_weight") }}
            {% else %}
              {{ states("sensor.weight_name_jiri") }}
            {% endif %}
        unit_of_measurement: 'kg'
        icon_template: mdi:weight-kilogram