Hey, this is a known bug with the client-side auth token refresh. After a successful login, the agent works for a few messages, then the client stops attaching a valid token and all requests fail with ERROR_NOT_LOGGED_IN, even though the UI still shows you as logged in. Your account is fine, your Pro subscription is active and auth is working normally.
Temporary workaround: log out and log back in via Cursor Settings. This restores things, but the issue may come back.
We’ve reported and are tracking this issue, but I can’t share an ETA for a fix yet. I’ll post an update when we have one. Related thread here: Error_not_logged_in