The github action task is unstable and sometimes fails over time

The github action task is unstable and sometimes fails over time. The timeout is because the task is not executed. What is the problem?

ci:

name: sync

on:
  push:
    branches: [ master ]
  schedule:
    - cron:  '0 */8 * * *'
  # Allows you to run this workflow manually from the Actions tab
  workflow_dispatch:

jobs:
  sync-aliyun:

    runs-on: ubuntu-latest
    strategy:
      max-parallel: 4
      matrix:
        python-version: [3.7]

    steps:
    - uses: actions/checkout@v1
    - name: Set up Python ${{ matrix.python-version }}
      uses: actions/setup-python@v1
      with:
        python-version: ${{ matrix.python-version }}
    - name: Install dependencies
      run: |
        python -m pip install --upgrade pip
        pip install -r requirements.txt
        sudo apt-get -y update
        sudo apt-get -y install skopeo
        skopeo --version
    - name: generate_sync_yaml
      timeout-minutes: 10
      run: |
        python generate_sync_yaml.py
    
    - name: sync image
      env:
        HUB_USERNAME: ${{ secrets.HUB_USERNAME }}
        HUB_PASSWORD: ${{ secrets.HUB_PASSWORD }}
      run: |
        bash sync.sh

log:

actions: