Chats disappearing and conversations getting scrambled after new Copilot update

I wanted to post this because I was looking for a solution and found this thread. I am experiencing a very similar issue with Microsoft 365 Copilot using a work account.

In my case, completed responses can disappear after I switch tabs, leave Copilot, and return. Sometimes they later reappear, but not consistently. I have also found older conversations that are now incomplete. I have reproduced the problem across different browsers, Incognito/InPrivate, a mobile phone, and another computer/network, so I opened a Microsoft support case.

During my most recent call, the support engineer told me that a data file intended to enhance Copilot search had become corrupted and was causing an “overlap” affecting search history and search results. I was told that Microsoft is working on the backend issue and rolling out an update, which may take some time. I was also told that this is a known issue affecting multiple users and that an internal service-health investigation is underway, although it is not currently visible as a public service-health notice. 

I have asked Microsoft to keep my support case open and provide updates. We’ll see. If I receive written confirmation or other meaningful information I can share publicly, I will update this thread.

Hopefully this helps others dealing with the same problem.