Gpt-4o and gpt-4o-mini family fine-tuned models failing

We are using gpt-4o and gpt-4o-mini fine-tuned models in production. As of this morning they were working fine (02/19/26), but as of ~20:50 UTC we began to experience complete and consistent failures for all chat completion requests using those fine-tuned models. The base models themselves are working as expected.

Here is the error message:

Chat completion failed: Error code: 400 - {‘error’: {‘message’: ‘There was an issue with your request. Please check your inputs and try again’, ‘type’: ‘invalid_request_error’, ‘param’: None, ‘code’: None}}

Attached is a screenshot, demonstrating the same error occuring in the OpenAI Platform Playground.