Dear Detective,
The Mirror System had a sudden server failure at 4/20 01:20 (UTC/GMT: +8:00). Some agents are unable to log in or cannot be matched, which is being resolved. We will notify you separately after the server is opened. Please forgive me for the inconvenience caused by the agent simulation training!
4/20 Announcement on maintenance of server failures
Source: Steam Community (opens in a new tab)