Dashboard Assistant Missing Chat History (Gemini)

Versions (relevant - OpenSearch/Dashboard/Server OS/Browser):
3.1.0

Describe the issue:
To use the Gemini 2.0 Flash model with the Dashboard Assistant, I set it as the os_chat_root_agent. However, multi‑turn conversations are not working. Although the conversationId is passed correctly, the history does not seem to be delivered. If anyone has resolved a similar issue, I would greatly appreciate your assistance.
Thank you for your attention.