Error 500

[townsmcp]

Now that Torbox is working again, I have followed the instructions and have Krantorbox installed and configured. However, when I add a request via Radarr I am getting an error 500 in the logs - nothing is uploading/downloading.
Logs show me:

2024/12/17 11:59:32 Krantorbox Auto-Upload Started
2024/12/17 11:59:32 Watching folder: /blackhole
2024/12/17 11:59:32 TorBox API Base: https://api.torbox.app
2024/12/17 11:59:32 TorBox API Version: v1
2024/12/17 11:59:32 File deletion after upload is enabled
2024/12/17 11:59:32 Watching folder: /blackhole
2024/12/17 12:00:01 New file detected: /blackhole/ZZZZZZZZZZZZZZ.magnet
2024/12/17 12:00:03 Attempt 1 failed: unexpected status code: 500. Retrying in 5s...
2024/12/17 12:00:09 Attempt 2 failed: unexpected status code: 500. Retrying in 5s...
2024/12/17 12:00:14 Attempt 3 failed: unexpected status code: 500. Retrying in 5s...
2024/12/17 12:00:19 Error uploading /blackhole/ZZZZZZZZZZ.magnet: failed to upload after 3 attempts

Just for clarity, I have installed this today for the first time. I have also set the config correctly based on Radarr location settings. My docker-compose.yml file is:

services:

  krantorbox:
    container_name: krantorboxRadarr
    image: krantorbox:local
    environment:
      - TORBOX_API_KEY=ZZZZZZZZZZZZZZZ
      - TORBOX_WATCH_FOLDER=/blackhole
      - DELETE_AFTER_UPLOAD=true
    volumes:
      - /mnt/symlinks/radarrtorbox:/blackhole
    restart: unless-stopped
    networks:
      - proxy

networks:
  proxy:
    driver: bridge
    external: true

Any suggestions for how to fix this?