AWS-StartEC2Instance timeout

Question

It appears that the AWS-StartEC2Instance Automation does not work.   
I have a Maintenance Window with a Task targeting an instance by ID. When the MW executes, it fails with the following error:   
_Automation Step Execution fails when it is verifying the instance(s) have reached desired state._   
_Get Exception from DescribeInstanceStatus API of ec2 Service._   
_Exception Message from DescribeInstanceStatus API:_   
_Request has expired. (Service: AmazonEC2; Status Code: 400; Error Code: RequestExpired; Request ID: a6647f3c-f218-451c-adb8-8a670236c1c0)._   
_Please refer to Automation Service Troubleshooting Guide for more diagnosis details._  
I have specified a role configured according to https://docs.aws.amazon.com/systems-manager/latest/userguide/automation-walk-security-assume.html.  
Note that the AWS-StopEC2Instance does execute without error.   
Has anyone out there had success using this Automation?

Answer

After splunking through the CloudTrail logs, I was able to determine that the problem was related to our use of encrypted EBS volumes (encrypted with our own KMS key).  I needed to grant kms:CreateGrant to the role that is executing the automation

AWS-StartEC2Instance timeout

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