Bug with Challenge about Kord 6P67

Hello,
I would like to report a problem with the fact that I have a bugged weapon called Kord 6P67, Rapid Fire is completely finished, but the weapon is the only one that did not unlock for me, I tried to verify the game files, reinstall the game. Various tips that I found on support or on the networks. Nothing helped me, please if it can be fixed somehow....