Pipeline Rules aren't working as intended

GitLab CI/CD
,
1

So I have two protected environments stage and prod and I’m trying to achieve the following :

  • Trigger child pipeline when a merge request is opened and the target branch is protected and stage
  • Trigger child pipeline when MR is merged to a protected branch and the branch name is stage
  • Don’t trigger child pipeline on opened merge requests for a protected environment and the with the name prod
  • Trigger pipeline when MR is merged to a protected environment and the environment name is prod
build:
  stage: build
  rules:
    - if: $CI_MERGE_REQUEST_ID && ($CI_COMMIT_REF_PROTECTED && $CI_COMMIT_REF_NAME == "stage")
      when: always 
    - if: $CI_MERGE_REQUEST_ID && ($CI_COMMIT_REF_PROTECTED && $CI_COMMIT_REF_NAME == "prod")
      when: never 
  trigger:
    include: 
      - local: myapp/.gitlab-ci.yml
    strategy: depend

Unfortunately, these rules don’t trigger the child pipeline for the job it’s specified for when I opened a MR for the stage protected branch. I’d appreciate any help.