Custom wake word isn't working - wake word component is marked as failed

The problem

After following the instructions at https://esphome.io/components/micro_wake_word.html, I am having trouble getting my custom wake word to work. okay_nabu works great, and my custom .tflite file works well with openWakeWord.

hey_greenwood.json logs_basement-office-speaker_run.txt

Which version of ESPHome has the issue?

2024.4.1

What type of installation are you using?

Home Assistant Add-on

Which version of Home Assistant has the issue?

2024.4.4

What platform are you using?

ESP32

Board

onju

Component causing the issue

micro_wake_word

Example YAML snippet

micro_wake_word:
  #model: okay_nabu # this works fine
  model: http://192.168.1.2:8123/local/microwakeword/hey_greenwood.json # also tried https://fqdn
  on_wake_word_detected:
    - if:
        condition: media_player.is_playing
        then:
          - media_player.pause
    - voice_assistant.start:
        wake_word: !lambda return wake_word;

Anything in the logs that might be useful for us?

[21:25:14][C][micro_wake_word:057]: microWakeWord:
[21:25:14][C][micro_wake_word:058]:   Wake Word: hey greenwood
[21:25:14][C][micro_wake_word:059]:   Probability cutoff: 0.500
[21:25:14][C][micro_wake_word:060]:   Sliding window size: 10
[21:25:14][E][component:082]:   Component micro_wake_word is marked FAILED

Additional information

The .json file and .tflite are hosted under the config/www directory in home assistant, and this URL is reachable internally.

esphome / issues

Custom wake word isn't working - wake word component is marked as failed #5743