Why doesn't my container app job scale up when there are messages on the queue?

Question

I have a container app job in Azure, and an Azure Storage Queue. The container app job should scale up when there are messages on the queue, and scale down to zero when the queue is empty. Here is the configuration for the job:

"eventTriggerConfig": {
    "parallelism": 1,
    "replicaCompletionCount": 1,
    "scale": {
      "maxExecutions": 10,
      "minExecutions": 0,
      "pollingInterval": 30,
      "rules": [
        {
          "auth": [
            {
              "secretRef": "connection-string-secret",
              "triggerParameter": "connection"
            }
          ],
          "metadata": {
            "accountName": "my-account-name",
            "queueLength": "1",
            "queueName": "my-queue-name"
          },
          "name": "queue-job",
          "type": "azure-queue"
        }
      ]
    }
  }

Nothing happens when new messages are put on the queue. KEDA keeps printing "Created 0 jobs" to the logs, so it seems that it is running.

What is wrong with this configuration?