https://www.gamespot.com/articles/fortnites-new-close-encounters-mode-temporarily-di/1100-6459203/

Fortnite's latest limited-time mode has been temporarily postponed. Shortly after the Close Encounters event began, Epic Games announced on Twitter that an issue had been discovered and the mode was being disabled across all platforms--PS4, Xbox One, PC, and iOS--while the developer investigated it.

Close Encounters was slated to be the second new limited-time mode in Fortnite: Battle Royale this week, following on the heels of Solid Gold v2, which began with the release of the 4.2 content update. In contrast to Solid Gold, Close Encounters mode focuses on "close quarters combat" and only features shotguns and the newly added jetpacks.