Greetings & Welcome to the Microsoft Q&A forum! Thank you for sharing your query.
It seems that the issues you're experiencing with your GPT-4o-mini assistants disappearing and files not being uploaded could be related to the stateful nature of the Assistants API. The API retains data such as threads, messages, and runs, but if there are problems with the API calls or if the assistants are being unintentionally deleted, it may not be immediately clear why this is happening.
Unfortunately, the provided context does not specify a way to view historical API calls directly. You might want to check your implementation to ensure that the assistants are being managed correctly and that the API calls are being logged or monitored in your system.
kindly refer these document https://learn.microsoft.com/en-us/azure/ai-services/openai/assistants-reference?tabs=python#delete-assistant
I hope these helps you. Thank you!