Promtail parsing JSON - dry-run does not parse labels

Question

I can't seem to get this to parse any labels in a dry run (or when pushing data into Loki either).

[inspect: timestamp stage]: none ends up empty

Any idea why? The config file is properly formatted YAML. I have tried multiple versions of promtail and no success.

cat dev.log | promtail --config.file promtail-config.yml --stdin --dry-run --inspect

server:
  http_listen_port: 9080
  grpc_listen_port: 0

positions:
  filename: /tmp/positions.yaml

clients:
  - url: "http://loki:3100/loki/api/v1/push"

scrape_configs:
  - job_name: api-ingest
    pipeline_stages:
      - json:
          expressions:
            timestamp: timestamp
            message: message
            app_name: app_name
            level: level
            app_url: app_url
      - labels:
          level:
          app_name:
          app_url:
          message:
      - timestamp:
          source: timestamp
          format: RFC3339
    static_configs:
      - targets:
          - localhost
        labels:
          job: "api-ingest"
          environment: "prod"
          __path__: /mylogfile.log

Logfile:

{"timestamp":"2024-02-21T14:06:37-06:00","app_name":"m-app-production","app_url":"http://192.168.1.100:3001","level":"INFO","message":"Cron is disabled: not scheduling jobs"},
{"timestamp":"2024-02-21T14:06:38-06:00","app_name":"m-app-production","app_url":"http://192.168.1.100:3001","level":"INFO","message":"connecting to Redis..."},
{"timestamp":"2024-02-21T14:06:38-06:00","app_name":"m-app-production","app_url":"http://192.168.1.100:3001","level":"INFO","message":"Redis connected"},

Clients configured:
----------------------
url: http://loki:3100/loki/api/v1/push
batchwait: 1s
batchsize: 1048576
follow_redirects: true
enable_http2: true
backoff_config:
  min_period: 500ms
  max_period: 5m0s
  max_retries: 10
timeout: 10s
tenant_id: ""
drop_rate_limited_batches: false
stream_lag_labels: ""

[inspect: timestamp stage]: none
2024-02-22T11:04:20.083141803-0600  {job="api-ingest"}  {"timestamp":"2024-02-21T14:06:37-06:00","app_name":"m-app-production","app_url":"http://192.168.1.100:3001","level":"INFO","message":"Cron is disabled: not scheduling jobs"},
[inspect: timestamp stage]: none
2024-02-22T11:04:20.083143146-0600  {job="api-ingest"}  {"timestamp":"2024-02-21T14:06:38-06:00","app_name":"m-app-production","app_url":"http://192.168.1.100:3001","level":"INFO","message":"connecting to Redis..."},
[inspect: timestamp stage]: none
2024-02-22T11:04:20.08314537-0600   {job="api-ingest"}  {"timestamp":"2024-02-21T14:06:38-06:00","app_name":"m-app-production","app_url":"http://192.168.1.100:3001","level":"INFO","message":"Redis connected"},