Glance card option "color icons based on state"

How is this supposed to work.
I can’t see an explanation in docs nor anyone with an example.
I have a bunch of binary sensors in a glance card. I want the icon colour to reveal its state.

Untitled

Thanks for responding @tom_l
That is the option I am referring to.
I select it and nothing happens to my icons if I change their state from ‘off’ to ‘on’ or similar.
glance

I just tried it with a climate device and two binary sensors. State colour worked for me (for the binary sensors).

What version of home assistant are you running?

Ignore me. I found that the theme I had selected was the issue.