Alert topics not resolved from parameter store

[sopeters]

I'm having trouble to lookup the topics from parameter-store which seemed to have worked in a previous version.
The actual Alarms are created but the Actions are missing.

service: test
variablesResolutionMode: 20210326
frameworkVersion: '2'

custom:
  alerts:
    topics:
      ok: ${ssm:/default/SNSNotificationListARN}
    alarms:
      - functionErrors

plugins:
  - serverless-plugin-aws-alerts

• Serverless Framework Version: 2.68.0
• serverless-plugin-aws-alerts: 1.7.4