Super user elastic can't run as regular user

Shouldn't elastic user be able to run_as anyone?

I have a proxy in front of Kibana and in the past I could set it to run as a user
I would use the elastic user to authenticate and then run as someone else. Now it's saying I can't do that. It says elastic user in superuser group can't run as some other user.

But when I call the Elastic api directly it works fine:

curl -H "es-security-runas-user: jacknich" -u elastic:password -X GET http://localhost:9200/

Nevermind. My user id was lowercase. I really wish user ids weren't case sensitive