Drone CI multiple triggers

Question

I have successfully set up a pull request trigger for our Drone CI but as soon as I added the cron trigger the pull requests trigger stops working. The working configuration is as bellow:

trigger:
  event:
    - pull_request

The edited trigger is:

trigger:
  event:
    - pull_request
    - cron
  cron:
    - nightly

Any idea why it is causing this? Maybe the configuration is wrong but I could not find anything else beside this in the docs.