Problem With 100% Lego Dc Super Villains

[tacoscratcher]

I am at 99.7 percent completion with all challenges except file finder completed. I used cheat codes for some of the characters but later went back to break open the folders for those characters. However, I am missing one gold brick and one character. The one gold brick I am missing is the one for the file finder challenge. But for some reason, it won't let me complete it. Yes, I know I said I am missing one character but that is Lex Luthor's Mech. And the only way to unlock that is if I have all the gold bricks. I am missing one, but I can't complete the file finder! Any solutions? Thanks!