it's bugged, seem to be cool down goes from when you 1st play the mission. so instead of resetting each week... it resets based on when you 1st played the mission that week. and if you have played after the new week starts but before your timer is reset... pooh no rewards cause the system thinks it already gave it to ya.
yeah.
so each week, if you dont see the reward box... dont play till you do.