If you see dag runs that are marked as success but don’t have any task runs, this means the dag runs’ execution_date was earlier than the dag’s start_date.
This is most commonly seen when the start_date is set to some dynamic value e.g. airflow.utils.dates.days_ago(0). This creates the opportunity for the execution date of a delayed dag execution to be before what the dag now thinks is it’s start_date. This can even happen in a cyclic pattern, where a few dagruns will work, and then at the beginning of every day a dagrun will experience this problem.
This simplest way to avoid this problem is the never use dynamic start_date. It is always better to specify a static start_date. If you are concerned about accidentally triggering multiple runs of the same dag, just set catchup=False.