Hi CHRIS WALMSLEY,
I can understand how concerning this must be when the affected chat contains information you really need.
Since your other chats are opening normally, this seems to be limited to that particular conversation. Please don’t delete it for now.
Could you let me know whether you’re using the Copilot app or a web browser and whether you’re signed in with a personal or work/school account? If possible, please also try opening the same chat from another browser or device using the same account.
You can also fully close and reopen Copilot, then double-check that you’re using the same account and sign-in method as before the update. If the chat still won’t open anywhere, please submit feedback through the app and mention that the issue started after the update, affects only one chat and leaves it stuck on a blank loading screen after refreshing.
Please let me know what happens when you try it from another browser or device and I’ll be happy to help you narrow it down further.