Django Celery Beat sending many-per-hour tasks but not daily tasks

This is a really weird situation. Tasks that are scheduled to run every several minutes every hour of the day (e.g. "*/20 * * * *") are being sent to Celery (with entries in Celery Beat's log) and Celery is running them. Tasks that are to be run once per day (e.g. "15 11 * * *") are not happening at their designated times though, and nothing is being written to Celery Beat's log for those.

I have checked the contents of the tables in the database, and everything looks right, except, of course, that last_run_at is null for the tasks that are not being sent.

# select * from django_celery_beat_periodictask where id=7;
 id |                     name                     |              task               | args | kwargs | queue | exchange | routing_key | expires | enabled | last_run_at | total_run_count |         date_changed          | description | crontab_id | interval_id | solar_id | one_off | start_time | priority | headers | clocked_id | expire_seconds
----+----------------------------------------------+---------------------------------+------+--------+-------+----------+-------------+---------+---------+-------------+-----------------+-------------------------------+-------------+------------+-------------+----------+---------+------------+----------+---------+------------+----------------
  7 | hub_builtin__dhmaintenance.tasks.rotate_logs | dhmaintenance.tasks.rotate_logs | []   | {}     |       |          |             |         | t       |             |               0 | 2025-09-25 04:39:20.172338+00 |             |          6 |             |          | f       |            |          | {}      |            |

# select * from django_celery_beat_crontabschedule where id=6;
 id | minute | hour | day_of_week | day_of_month | month_of_year | timezone
----+--------+------+-------------+--------------+---------------+----------
  6 | 30     | 0    | *           | *            | *             | UTC

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