AWS::CloudFormation::Init yum update fails

Got a little problem, so part of my json file I want to run a command to update all the packages the following command is:

        "commands" : {
          "update_yum_packages" : {
            "command" : "sudo yum update -y"
          }
        },

Now if I remove this from my json file the stack will create with no issues, however when I add the command I get an error from AWS::CloudFormation::WaitCondition. I have set the timeout to 1200 is there something clearly wrong here ?

I can run the command fine once I ssh onto the new instance.