Default admin role misses permissions to edit cluster settings

With a default configuration, I tried to PUT to /_settings

I got the following response:

{"error":{"root_cause":[{"type":"security_exception","reason":"no permissions for [] and User [name=admin, roles=[admin], requestedTenant=null]"}],"type":"security_exception","reason":"no permissions for [] and User [name=admin, roles=[admin], requestedTenant=null]"},"status":403}

Which I figured was strange. Is there a way to solve this?

Would appreciate a reply if anyone has any ideas.