Random response from new transcribe models

I’m testing new transcription models (gpt-4o-transcribe, gpt-4o-mini-transcribe) for the Latvian language, but every time I use client.audio.transcriptions.create, it returns random text - usually a single sentence unrelated to the audio. Here’s an example:


The older model (whisper-1) provides the correct result:

Other LLM models (e.g., gemini-2.0-flash) also return the correct result for the same audio file:
.

I have tested gpt-4o-transcribe with English audio, and it produced the correct result.

I’m using the following code to create a transcript:

from IPython.display import Markdown
from openai import OpenAI

client = OpenAI(api_key='API_KEY')

audio_file = open("D:/Downloads/20250416_1332_24min.mp3", "rb")
# First 24 min from this source: https://med.latvijasradio.lv/saeima/20250416_1332.mp3

transcription = client.audio.transcriptions.create(
    model="gpt-4o-transcribe", 
    file=audio_file,
    prompt='transkribē šīs Saeimas debates',
    language='lv',
    response_format="json"
)

print(transcription.text)

transcription_mini = client.audio.transcriptions.create(
    model="gpt-4o-mini-transcribe", 
    file=audio_file,
    prompt='transkribē šīs Saeimas debates',
    language='lv',
    response_format="json"
)

print(transcription_mini.text)

transcription_lv_wh = client.audio.transcriptions.create(
  file=audio_file,
  model="whisper-1",
  language="lv",
  response_format="verbose_json",
  timestamp_granularities=["segment"]
)

Markdown(transcription_lv_wh.text)

Any idea why these new transcript models generate random text, even though Latvian is one of the supported languages?

I have Python version: 3.12.4 and openai version: 1.75.0