How unusual, it works flawless for me.
When you specify the chunking_strategy parameter, does it still gives an error?
audio_file = open("yourfile.mp3", "rb")
transcript = client.audio.transcriptions.create(
file=audio_file,
model="gpt-4o-transcribe-diarize",
response_format="diarized_json",
chunking_strategy="auto",
)
print(transcript.text,transcript.to_dict())