Usual way of defining periodic tasks in celery not working as expected

[mrn-aglic]

From the docs, it should be possible to define a periodic task like this:

app.conf.beat_schedule = {
    'add-every-30-seconds': {
        'task': 'tasks.add',
        'schedule': 30.0,
        'args': (16, 16)
    },
}

However, when I do it like that in my setup:

      app.conf.beat_schedule = {
          "example": {
              "task": print_task.pipeline.s().name,
              "schedule": 4
          }
      }

the task is executed twice, after which it disappears from the readbeat Redis location.
Also, adding tasks with the built in add_periodic_task makes them appear for a moment, but they disappear from Redis before being executed even once.

The entire repo is here: https://github.com/mrn-aglic/celery-reset-schedule

The schedules are setup in: reset_schedule > beat > __init__.py