serverless frameworkでcloudwatch eventsが作成されない

お世話になります。

lambda functionを用いてec2のAMIのbackupを定期的に取得する方法を作成しています。

参考にしたサイトは以下になります。
https://qiita.com/tonishy/items/74e145f8c9cba031fa01

参考サイトに従う形でのlambda function作成は成功しました。
次のステップとしてserverless frameworkに環境を落とし込むことを検討しています。

下記のserverless.ymlでdeployするとsuccessはしています。

service: ec2-backup-new

provider:
  name: aws
  runtime: python3.6
  region: ap-northeast-1
  role: arn:aws:iam::XXXXXXXXXXXX:role/ec2-backup-test

functions:
  ec2-image-backup:
    handler: ec2-image-backup.lambda_handler
    environment:
      AWS_ACCOUNT: 'XXXXXXXXXXXX' # AWSアカウントを記述
    events:
      - schedule: cron(0 9 * * ? *) #バックアップを実行したい時間をcron式で記述
  delete_snapshot_after_ami_deregister:
    handler: delete_snapshot_after_ami_deregister.lambda_handler
    environment:
      AWS_ACCOUNT: 'XXXXXXXXXXXX' # AWSアカウントを記述
    events:
      - cloudwatchEvent:
        enabled: true
        event:
          source:
            - "aws.ec2"
          detail-type:
            - "AWS API Call via CloudTrail"
          detail:
            eventSource:
              - "ec2.amazonaws.com"
            eventName:
              - "DeregisterImage"

しかし、以下の部分だけのAWSが作成されません。
cloudformationのログを見てもこのリソースに関する出力は無いようです。

    events:
      - cloudwatchEvent:
        enabled: true
        event:
          source:
            - "aws.ec2"
          detail-type:
            - "AWS API Call via CloudTrail"
          detail:
            eventSource:
              - "ec2.amazonaws.com"
            eventName:
              - "DeregisterImage"

sls deploy時のターミナルのログです。

mac11:ec2-backup-new $ sls deploy --verbose
(node:99826) ExperimentalWarning: The fs.promises API is experimental
Serverless: Packaging service...
Serverless: Excluding development dependencies...
Serverless: Creating Stack...
Serverless: Checking Stack create progress...
CloudFormation - CREATE_IN_PROGRESS - AWS::CloudFormation::Stack - ec2-backup-new-dev
CloudFormation - CREATE_IN_PROGRESS - AWS::S3::Bucket - ServerlessDeploymentBucket
CloudFormation - CREATE_IN_PROGRESS - AWS::S3::Bucket - ServerlessDeploymentBucket
CloudFormation - CREATE_COMPLETE - AWS::S3::Bucket - ServerlessDeploymentBucket
CloudFormation - CREATE_COMPLETE - AWS::CloudFormation::Stack - ec2-backup-new-dev
Serverless: Stack create finished...
Serverless: Uploading CloudFormation file to S3...
Serverless: Uploading artifacts...
Serverless: Uploading service .zip file to S3 (4.87 KB)...
Serverless: Validating template...
Serverless: Updating Stack...
Serverless: Checking Stack update progress...
CloudFormation - CREATE_COMPLETE - AWS::CloudFormation::Stack - ec2-backup-new-dev
CloudFormation - UPDATE_IN_PROGRESS - AWS::CloudFormation::Stack - ec2-backup-new-dev
CloudFormation - CREATE_IN_PROGRESS - AWS::Logs::LogGroup - Ec2DashimageDashbackupLogGroup
CloudFormation - CREATE_IN_PROGRESS - AWS::Logs::LogGroup - DeleteUnderscoresnapshotUnderscoreafterUnderscoreamiUnderscorederegisterLogGroup
CloudFormation - CREATE_IN_PROGRESS - AWS::Logs::LogGroup - Ec2DashimageDashbackupLogGroup
CloudFormation - CREATE_COMPLETE - AWS::Logs::LogGroup - Ec2DashimageDashbackupLogGroup
CloudFormation - CREATE_IN_PROGRESS - AWS::Logs::LogGroup - DeleteUnderscoresnapshotUnderscoreafterUnderscoreamiUnderscorederegisterLogGroup
CloudFormation - CREATE_COMPLETE - AWS::Logs::LogGroup - DeleteUnderscoresnapshotUnderscoreafterUnderscoreamiUnderscorederegisterLogGroup
CloudFormation - CREATE_IN_PROGRESS - AWS::Lambda::Function - Ec2DashimageDashbackupLambdaFunction
CloudFormation - CREATE_IN_PROGRESS - AWS::Lambda::Function - DeleteUnderscoresnapshotUnderscoreafterUnderscoreamiUnderscorederegisterLambdaFunction
CloudFormation - CREATE_IN_PROGRESS - AWS::Lambda::Function - Ec2DashimageDashbackupLambdaFunction
CloudFormation - CREATE_IN_PROGRESS - AWS::Lambda::Function - DeleteUnderscoresnapshotUnderscoreafterUnderscoreamiUnderscorederegisterLambdaFunction
CloudFormation - CREATE_COMPLETE - AWS::Lambda::Function - Ec2DashimageDashbackupLambdaFunction
CloudFormation - CREATE_COMPLETE - AWS::Lambda::Function - DeleteUnderscoresnapshotUnderscoreafterUnderscoreamiUnderscorederegisterLambdaFunction
CloudFormation - CREATE_IN_PROGRESS - AWS::Lambda::Version - DeleteUnderscoresnapshotUnderscoreafterUnderscoreamiUnderscorederegisterLambdaVersionF86v48XmogxGwz13oRdeqOOXvatKQma1lOtaKDnRtw
CloudFormation - CREATE_IN_PROGRESS - AWS::Lambda::Version - Ec2DashimageDashbackupLambdaVersionGTVn9UWPxL2FHKuc0jSf9SmjwXxvx584Bql3nYbEyM
CloudFormation - CREATE_IN_PROGRESS - AWS::Events::Rule - Ec2DashimageDashbackupEventsRuleSchedule1
CloudFormation - CREATE_IN_PROGRESS - AWS::Events::Rule - Ec2DashimageDashbackupEventsRuleSchedule1
CloudFormation - CREATE_IN_PROGRESS - AWS::Lambda::Version - DeleteUnderscoresnapshotUnderscoreafterUnderscoreamiUnderscorederegisterLambdaVersionF86v48XmogxGwz13oRdeqOOXvatKQma1lOtaKDnRtw
CloudFormation - CREATE_IN_PROGRESS - AWS::Lambda::Version - Ec2DashimageDashbackupLambdaVersionGTVn9UWPxL2FHKuc0jSf9SmjwXxvx584Bql3nYbEyM
CloudFormation - CREATE_COMPLETE - AWS::Lambda::Version - DeleteUnderscoresnapshotUnderscoreafterUnderscoreamiUnderscorederegisterLambdaVersionF86v48XmogxGwz13oRdeqOOXvatKQma1lOtaKDnRtw
CloudFormation - CREATE_COMPLETE - AWS::Lambda::Version - Ec2DashimageDashbackupLambdaVersionGTVn9UWPxL2FHKuc0jSf9SmjwXxvx584Bql3nYbEyM
CloudFormation - CREATE_COMPLETE - AWS::Events::Rule - Ec2DashimageDashbackupEventsRuleSchedule1
CloudFormation - CREATE_IN_PROGRESS - AWS::Lambda::Permission - Ec2DashimageDashbackupLambdaPermissionEventsRuleSchedule1
CloudFormation - CREATE_IN_PROGRESS - AWS::Lambda::Permission - Ec2DashimageDashbackupLambdaPermissionEventsRuleSchedule1
CloudFormation - CREATE_COMPLETE - AWS::Lambda::Permission - Ec2DashimageDashbackupLambdaPermissionEventsRuleSchedule1
CloudFormation - UPDATE_COMPLETE_CLEANUP_IN_PROGRESS - AWS::CloudFormation::Stack - ec2-backup-new-dev
CloudFormation - UPDATE_COMPLETE - AWS::CloudFormation::Stack - ec2-backup-new-dev
Serverless: Stack update finished...
Service Information
service: ec2-backup-new
stage: dev
region: ap-northeast-1
stack: ec2-backup-new-dev
api keys:
  None
endpoints:
  None
functions:
  ec2-image-backup: ec2-backup-new-dev-ec2-image-backup
  delete_snapshot_after_ami_deregister: ec2-backup-new-dev-delete_snapshot_after_ami_deregister

Stack Outputs
DeleteUnderscoresnapshotUnderscoreafterUnderscoreamiUnderscorederegisterLambdaFunctionQualifiedArn: arn:aws:lambda:ap-northeast-1:XXXXXXXXXXXX:function:ec2-backup-new-dev-delete_snapshot_after_ami_deregister:7
Ec2DashimageDashbackupLambdaFunctionQualifiedArn: arn:aws:lambda:ap-northeast-1:XXXXXXXXXXXX:function:ec2-backup-new-dev-ec2-image-backup:8
ServerlessDeploymentBucketName: ec2-backup-new-dev-serverlessdeploymentbucket-1czl9svgqonuv

serverless.ymlの記述が悪いのでしょうか。
お分かりになる方、アドバイスを頂けましたら幸いです。