Will the flex service tier be supported for GPT-5.1? It’s listed on the pricing page but via API I’m seeing this error:
status_code: 400, model_name: gpt-5.1, body: {'message': 'Flex is not available for this model.', 'type': 'invalid_request_error', 'param': None, 'code': None}
Same issue here - I am getting status code 400 - {‘error’: {‘message’: ‘Flex is not available for this model.’} when calling API with service_tier=“flex” for gpt-5.1-2025-11-13.
I am using the latest Python library (v2.8) and GPT5.1 is listed as supporting flex processing (https://platform.openai.com/docs/pricing?latest-pricing=flex).
I reproduced the issue and raised it with staff for review. Thanks for flagging it and I hope it gets resolved quickly.
Case closed, looks like it’s working now 
Thanks team for flagging! We resolved this earlier today - please let us know if you're still seeing any issues here.