2.4.5 및 stable assign 환경에서 사이트가 로드되지 않음

app.yml에서 플러그인의 stable 브랜치를 클론하나요?

네, 이렇게 합니다.

hooks:
  after_code:
    - exec:
        cd: $home/plugins
        cmd:
          - git clone https://github.com/discourse/docker_manager.git
          - git clone https://github.com/discourse/discourse-spoiler-alert.git
          - git clone https://github.com/discourse/discourse-styleguide.git
          - git clone --branch stable https://github.com/discourse/discourse-solved.git
          - git clone https://github.com/discourse/discourse-user-notes.git
          - git clone https://github.com/discourse/discourse-checklist.git
          - git clone --branch stable https://github.com/discourse/discourse-assign.git