How about trying to remove the role of Course creator in that course and simply giving the a person Teacher rights and then, go into the course and then from the gear menu top right > More>Users>Check permissions, check the permissions of that particular person to see if they have moodle/course:update set to Yes
Because I agree with Gareth that the problem must be with this capability.
Because I agree with Gareth that the problem must be with this capability.