I’m not sure HA supports Font Awesome icons, but if it does I’d bet the format is the same as material design icons which is mdi:icon-name-here. Have you tried fa:circle-notch?
@czoog is asking about icons in HAdashboard, not in HA.
ha dashboard does support font awsome icons.
and also icons that have a - in it should appear normally.
but FA and MDI sometimes put in new ones and they just appear when its updated in appdaemon.
so your first try icon_off: fa-circle-notch was right, but its probably an icon thats to new
To add to that - I am updating to the latest MDI icons in the next beta. The latest FA icons however are a large upgrade - not for me, but for you, the users, as they introduced many breaking changes, i.e. renamed a lot of icons. I can go ahead and make the upgrade but a lot of folks will have to go back and revisit their dashboards so I’m not keen on doing that with everything else that is changing in the beta.