V85 Circuit breaker Invalid

Prestige V85 Circuit breaker cannot be equipped which is super frustrating because I've done Vault 4 twice this weeks and couldn't get the gun. I also received a Gold Perimeter Key and the only weapon in the strong box was a Gold V85 and could even pick it up. This is incredible saddening and frustrating as someone who had put over 500 hours into the game, ive never had this problem.