Empty Cells in Calendar View

[a8356555]

I'm using airflow 2.9.1.
I have a job schedule at 00:30 every day, and I have found that some cells in my calendar view are empty.

Here is my dag's setting

default_args = {
    'max_active_runs': 1,
    'retries': 0,
}

with DAG(
    'my_dag',
    start_date=pendulum.now().in_timezone('Asia/Taipei').subtract(days=1),
    default_args=default_args,
    schedule_interval='30 0 * * *',
    # ...
) as dag:

I have checked that the jobs did succeed in those days.
Has anyone else encountered a similar issue?
Thanks in advance!

[a8356555]

Besides, after 10/28 and 10/29's empty cells, the dag did not run as expected at 10/30 00:30, and there is no error log in the scheduler or the trigger.
The green cell at 10/30 is from my manual execution after I found that today's job is not scheduled.