Packer file contents:
{
  "provisioners": [{
    "type": "ansible",
    "playbook_file": "../ansible/nexus.yml"
  }],
  "builders": [{
    "type": "amazon-ebs",
    "region": "us-east-2",
    "source_ami_filter": {
        "filters": {
            "virtualization-type": "hvm",
            "name": "amzn-ami-hvm*-gp2",
            "root-device-type": "ebs"
        },
        "owners": ["137112412989"],
        "most_recent": true
    },
    "instance_type": "t2.medium",
    "ami_virtualization_type": "hvm",
    "ssh_username": "ec2-user",
    "ami_name": "Nexus (Latest Amazon Linux Base) {{isotime \"2006-01-02T15-04-05-06Z\"| clean_ami_name}}",
    "ami_description": "Nexus AMI",
    "run_tags": {
        "AmiName": "Nexus",
        "AmiCreatedBy": "Packer"
    },
    "tags": {
        "Name": "Nexus",
        "CreatedBy": "Packer"
    }
  }]
}
I end up with this error
Timeout (12s) waiting for privilege escalation prompt: or Connection to 127.0.0.1 closed.\r\n