[MegaBlues]

In a level 60 Giant Whirlpool, today at this time, there was a floor of the dungeon that no monsters could be found in. However, the floor refused to give the "This floor is quiet" clear message.

There may be some sort of issue with random generation?

EDIT: This also forced a partial clear, just for more information.

[GameMaster85]

Might be one of those extremely rare dungeons that have mobs in a box room with no entrances.