Knowledge base disconnected from chatGPT agent

I am testing the chatGPT agent flow and everything is working fine. Almost going to launch for UAT, suddenly the agent seems to be disconnected from the knowledge base and cannot read the documents in the knowledge base, keep getting back “as an AI model my data is not updated…ba ba ba”.
I remove the documents in the knowledge base, and upload them again, which doesn’t help. Anyone can help?