That moment, when you've been saving Vanguard marks because you weren't sure what to spend them on, and you check your inventory after painstakingly completing all the strikes for all 100 marks that week, only to find that your marks are still stuck at 200, and you realize that, although there is no warning or notification of any sort, there's a hard cap of 200, and there's no way to get any of the extra wasted marks back.