Tests are not running at scheduled time

Running Tests
1

I have such config:

version: 2
jobs:
  selenium:
    machine: true
    steps:
      - run:
......
workflows:
  version: 2
  oncommit-build:
    jobs:
      - selenium:
          filters:
            branches:
              only:
                - master
  nightly-build:
    triggers:
      - schedule:
          cron: "30 * * * *"
          filters:
            branches:
              only:
                - staging
    jobs:
      - selenium

CI runs oncommit-build task on commit successfully.
But it doesn’t run nightly-build task at specific time, in my case every hour.
I’m using the company’s CI, there are always some tasks running at the same time, can be this affect my scheduled task?
What else might be a problem here?