A bug causing some Borderlands 2 players to lose Badass Rank and Golden Keys is unrelated to a patch and DLC released yesterday for the game.
Badass Rank relates to weapon proficiency players achieve through completing challenges, while Golden Keys are rare items which unlock valuable weapon chests.
"2K and Gearbox have been working steadily to fix a bug reported to us by fans that resets Badass Rank, and while this bug has only been affecting a very small number of players worldwide and does not affect the ability to play Borderlands 2, addressing this issue is still very important to us," the publisher told Polygon.
"We ask that players who have experienced this issue to email us at email@example.com with as many details as possible to help us gather additional information so that we can squash this reported bug.
"Coincidentally, a patch was released today and the fifth playable character class, Gaige the Mechromancer, became available for purchase and download today across PlayStation 3, Xbox 360 and PC via Steam.
"The patch and the Mechromancer downloadable character class are in no way related to the Badass Rank issue, and fans can feel confident when downloading either item. A further compatibility update will follow in the coming days to address connectivity issues between those who have the Mechromancer and those who do not."
Gearbox previously announced plans to release four Borderlands 2 DLC campaign add-ons. Retailing individually for $9.99, they'll each feature "several hours of gameplay and introduce new adventures, allies, enemies and environments". A Borderlands 2 Season Pass enabling players to pre-purchase the DLC at a discount is available now.