Cron Job errors not showing in logs

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A test cron_job was added to our crontab with intentionally faulty logic; the cron job calls a nonexistent stored procedure.

SELECT cron.schedule('process-updates', '10 seconds', 'CALL nonexistent_procedure()');

Failures are recorded in cron.job_run_details but there are no error / failure statements in the postgres server logs. It would be expected to see something like 'COMMAND failed'.

Our settings:

log_min_messages = warning
client_min_messages = warning
cron.log_min_messages = warning

What am I missing?