To all you Reach fans out there I need help. When trying to complete the challenge "Fleet Feet" (which is where you have to complete any campaign mission on legendary under 12:00 minutes)it does not count the challenge as completed for some reason and three of my friends and I have completed this challenge 5 times all way under 12 minutes, one being 10:59. So if anyone knows what I may be doing wrong, please let me know.