Users from different regions of the world report disappearing chat histories in the ChatGPT navigation column. There seems to be an error in the delivery of content from the server, because with a workaround - display the respective chats from the browser history - the disappeared chats can be displayed. Remarkable that on the status page https://status.openai.com/
no malfunction for chat.openai.com is documented s. Screenshot bottom. Addendum 2023-03-08.
See also . Users who have booked ChatGPT Plus
also report this fault.
 All previous ChatGPT history gone? 08.03.2023