https://www.gamespot.com/articles/fortnite-season-6s-big-new-item-shadow-stones-are-/1100-6462120/

Epic kicked off Season 6 of its popular battle royale game, Fortnite, but as is to be expected with an update of this scale, things haven't gone completely smoothly. A number of issues have cropped up following the release of the game's 6.0 update, including one that rendered it pretty much unplayable on Xbox One. That has since been resolved, but another bug has been found, this one relating to Shadow Stones, one of the new items Epic introduced to the game this week. [Update: The issue with Shadow Stones has been resolved and they are once again available in Fortnite, but Epic has had to temporarily disable another item, the Port-a-Fortress, due to a separate problem.]

On Twitter, the developer announced that an issue has been discovered with the new consumable items. As a result, Epic has temporarily disabled the stones until it can roll out a fix. The studio didn't provide an estimate as to how long that would take, so it's unclear when players can expect the stones to return to the game.