I could have sworn Flash Lite worked, but it did not. GPT Nano 5 definitely worked. It looks like this is a known issue even with Wordpress. here is a link for reference. What we need to do is whenever we are using a Gemini provider, to remove the additionalProperties item from the JSON Response Schema: Remove `additionalProperties` from the JSON response schema - Pull Request #18 - WordPress/ai-provider-for-google - GitHub