X_NOTIFY_DELIVERY_HELD
Means
another attempt holds this delivery
Typical cause
a live attempt holds the delivery claim, so this one neither sent nor treated the notification as gone out; the job retries once the claim is past its reclaim window
Fix
x jobs list --json — the run retries on its own once the claim can be reclaimed; to shorten that, set reclaimAfterMs on postgresDeliveryLedger()