Template Cover: Position slider grayed out

Hi all
i create this cover template to control open (position 100) /close (position 21) /tilt (between position 0 and 20) of a blind with a shelly2.5 shutter but Position Slider is grayed out.

What I’m doing wrong?
Tilt intermediate positions is not working well too but it’s another story!!!

- platform: template
  covers:
    shelly25_blind02:
      device_class: blind
      friendly_name: "Blind Bedroom 02"
      #value_template: "{{ states('cover.shellyswitch25_68c63af9d218') }}"
      availability_template: "{{ states('cover.shellyswitch25_68c63af9d218') != 'unavailable' }}"   
      position_template: >-
        {% if state_attr('cover.shellyswitch25_68c63af9d218', 'current_position') | float <= 21 %}
           {{ 0|int  }}
        {% else %}
           {{ state_attr('cover.shellyswitch25_68c63af9d218', 'current_position') }}
        {% endif %}
      tilt_template: >-
        {% if state_attr('cover.shellyswitch25_68c63af9d218', 'current_position') | float <= 21 %}
           {{ 100 - (state_attr('cover.shellyswitch25_68c63af9d218', 'current_position') | float / 21 * 100)|int  }}
        {% else %}
           {{ state_attr('cover.shellyswitch25_68c63af9d218', 'current_position') }}
        {% endif %}
      optimistic: true
      open_cover:
        service: 'cover.set_cover_position'
        data:
         entity_id: cover.shellyswitch25_68c63af9d218
         position: 100
      close_cover:
        service: 'cover.set_cover_position'
        data:
         entity_id: cover.shellyswitch25_68c63af9d218
         position: 21         
      stop_cover:
        service: 'cover.stop_cover'
        data:
         entity_id: cover.shellyswitch25_68c63af9d218
      set_cover_tilt_position:
        service: cover.set_cover_position
        data:
         entity_id: cover.shellyswitch25_68c63af9d218
         position: >-
           {{ state_attr('cover.shelly25_blind02', 'current_tilt_position') | int }}

template works well

also state is correct:
image

but on HA position is grayed out (name are in italian but it’s the same)
image

Tnx

I solved with support of developers. More info at https://github.com/home-assistant/core/issues/42954