Help Customizing entitiy Icons

Hey Everyone.

I’m having issues getting an entity to “register” my customizations.
The entity is a numeric slider (I’m going to use it as a volume slider) helper item I created in the GUI.
I then added the following to the customization yaml file.

input_number.vol_master_ensuite:
  icon_template: >
    {% if states('input_number.vol_master_ensuite') | float <= 20 %}
      mdi:volume-low
    {% elif states('input_number.vol_master_ensuite') | float > 20 and float < 40  %}
      mdi:volume-medium
    {% else %}
      mdi:volume-high
    {% endif %}

When I change the slider to over 20 the icon doesn’t change and also doesn’t change when I set the volume over 40. I’ve checked that the entity ID is correct.
I’m out of idea’s here.
The assigned icon is mdi:volume-low and that displays but it never changes.

Anyone have any experience with this?

Thank you.

As I’m aware, this method doesn’t work anymore. Use a customizable card instead, e. g. custom:button-card.

I’ll give that a bash then.

Thank you.