serverless-plugin-split-stacks: AppSync Api not found in stack. Did you forget to deploy?

I am getting the error AppSync Api not found in stack. Did you forget to deploy?.

Here is the environment and output.

✖ Stack tech-xxxxxx-dev failed to deploy (1353s)
Environment: darwin, node 18.13.0, framework 3.27.0 (local), plugin 6.2.3, SDK 4.3.2
Credentials: Local, "wgv-app-dev" profile
Docs: docs.serverless.com
Support: forum.serverless.com
Bugs: github.com/serverless/serverless/issues

Error:
AppSync Api not found in stack. Did you forget to deploy?

I am trying to migrate from V1 of the plugin using the migration guide.

All the resources appear to deploy for a short period of time before a ROLLBACK is issued. And then they disappear. I suspect that the Rollback is initiated by the serverless framework itself since the appsync plugin throws this error.

async getApiId() {
   this.loadConfig();

   if (!this.naming) {
     throw new this.serverless.classes.Error(
       'Could not find the naming service. This should not happen.',
     );
   }

   const logicalIdGraphQLApi = this.naming.getApiLogicalId();

   const { StackResources } = await this.provider.request<
     DescribeStackResourcesInput,
     DescribeStackResourcesOutput
   >('CloudFormation', 'describeStackResources', {
     StackName: this.provider.naming.getStackName(),
     LogicalResourceId: logicalIdGraphQLApi,
   });

   const apiId = last(StackResources?.[0]?.PhysicalResourceId?.split('/'));

   if (!apiId) {
     throw new this.serverless.classes.Error(
       'AppSync Api not found in stack. Did you forget to deploy?',
     );
   }

   return apiId;
 }

So apiId is not found for some reason which throws an exception.

I am probably missing something in my serverless.yml or do I need to explicitly Output some CloudFormation values to fix this.

Here is the header of my serverless yml file.

appSync:
  name: "${self:service}-${self:provider.stage}"
  authentication:
    type: AMAZON_COGNITO_USER_POOLS
    config:
      awsRegion: ${self:provider.region}
      defaultAction: ALLOW
      userPoolId:
        Fn::ImportValue: ${self:custom.resources.PROJECT_PREFIX}-UserPoolId
  additionalAuthentications:
    - type: API_KEY
  apiKeys:
    - name: Default-${self:provider.stage}
      description: Default-${self:provider.stage} generated by Serverless deployment
      expiresAfter: 1y
      apiKeyId: ${self:custom.resources.APPSYNC_API_KEY}
....

It would be very helpful if there is a working example available to compare with.

Thanks in advance.

O.,