Why i miss that last mission kill by V1 or jb-2. but i kill more than ten??

Yes, unfortunately it is a bug. You can contact eahelp.com to discuss your situation. Otherwise the Ratburner helmet will be available in an upcoming missing or by spending company coins. This bug also happened to me and other players I know. For future missions... I found that restarting the application until it starts tracking works, but working to get all of your points, just to find out it’s still not working is stressful.