title: Airflow scheduler is not picking up new tasks after upgrade from 1.10.4 to 2.2.3
body: <p>I recently upgraded from airflow 1.10.4 to 2.2.3</p>
  <p>Everything seems to be working fine, except when I create a new task, the scheduler does not pick it up (unless I restart it)</p>
  <p>It also does not appear under the DAG tasks in the server.</p>
  <p>How do I go about fixing this?</p>