Serverless, deploying ElasticSearch to AWS, "Creating elasticsearch domain did not stabilize"

I'm deploying through Github Actions my Serverless app onto AWS with Lerna, the full output is this one:

Serverless: Checking Stack update progress...
.......

 Serverless Error ---------------------------------------

  An error occurred: ElasticSearch - Creating Elasticsearch Domain did not stabilize..

  Get Support --------------------------------------------
     Docs:          docs.serverless.com
     Bugs:          github.com/serverless/serverless/issues
     Issues:        forum.serverless.com

  Your Environment Information ---------------------------
     Operating System:          linux
     Node Version:              14.4.0
     Framework Version:         1.65.0
     Plugin Version:            3.4.1
     SDK Version:               2.3.0
     Components Version:        2.22.3

I've tried following this:

Creating Elasticsearch service with AWS Cloudformation: "Creating Elasticsearch Domain did not stabilize"

Which points to:

https://mysteriouscode.io/blog/creating-elasticsearch-domain-did-not-stabilize-cant-create-aws-elasticsearch-5-1-with-cloudformation/

So, I added to my serverless.yml file:

...
ElasticSearch:
  Type: 'AWS::Elasticsearch::Domain'
  Properties:
    ElasticsearchVersion: 7.4
    EBSOptions:
      EBSEnabled: true
      VolumeType: gp2
      VolumeSize: 10
    ElasticsearchClusterConfig:
      InstanceType: ${self:custom.afex.${self:provider.stage}.InstanceType}
      InstanceCount: 1
      DedicatedMasterEnabled: false
    CognitoOptions:
      Enabled: true
      IdentityPoolId: us-east-2:7f7a3f74-xxxxx
      RoleArn: arn:aws:iam::590275261404:role/AfexAmazonESCognitoAccess
      UserPoolId: us-east-2_nbiyN8stf
    AdvancedOptions:    <--------- THIS ARE THE NEEDED LINES 
      indices.fielddata.cache.size: 40 <--------- THIS ARE THE NEEDED LINES 
      rest.action.multi.allow_explicit_index: true <--------- THIS ARE THE NEEDED LINES

But there's no change, still I have that error output. Any clue?