

Out of curiosity, is it something as simple as needing to wrap the template in quotes? I may be mixing up my YAML with the Ansible work I’ve been doing, but I think you need to have templates double quoted like this in order to resolve the jinja2 properly: "{{ state_attr('light.etc', 'brightness') }}
I don’t think you need the quotes in the Templates section of dev tools but you do in YAML files. I could be wrong though, let me know if you try it.
Definitely use the state_attr()
form over states.etc.etc
form. I think there’s something about how HA handles startup that may mess with templates if you use states.etc.etc
.
Ovo-lacto vegetarian, maybe?