Complete message:

We have confirmed an issue with the instance dungeon "The Navel (Hard)" which makes it possible for unintended strategies to be used to complete the dungeon. As a result of this, the instance dungeon will be temporarily closed off. If you are currently progressing in "The Navel (Hard)," you will be removed from the instance after 10 minutes. The issue is expected to be addressed in 4 to 5 hours. We apologize for any inconvenience this may cause and thank you for your understanding.