Microsoft Copilot Notebook conversation disappeared after apparent glitch

I use Microsoft Copilot with a personal Microsoft account. In a Copilot Notebook named “Job Hunting Updated”, I had an extensive long-running main conversation containing important personal career-planning work. The conversation name was "Job Hunting"

The conversation was available until today 10 pm Australia Eastern Time. Following what appeared to be a glitch, the main conversation disappeared and was replaced by a different/new conversation Name "Update Cv and cover Letter". I did not intentionally delete the original conversation.

I need Microsoft to investigate whether the original conversation still exists in server-side history, backups, telemetry, previous notebook state, or other recoverable storage, and whether it can be restored. I have downloaded the csv files from my account Microsoft Privacy Dashboard and the chat is not there.

Please do not treat this simply as a request for help locating chat history. I am specifically asking for investigation/recovery of a conversation that disappeared unexpectedly.

The lost conversation contained substantial work that cannot be recreated accurately.