Background Process hangs Test process

My background command refuses to run in background and hangs the whole build.

test:
  pre:
    - npm run test-server:
      background: true
  override:
    - npm run eslint
    - npm run lesshint
    - npm test
    - nightwatch -c test/browserstack.config.js -e chrome,firefox
    - nightwatch -c test/browserstack.config.js -e ie,safari

Did you fix? I have the same problem.

I didn’t find out causes of the problem. When I migrate v1.0 to v2.0, background process is properly running without hangs.