Adding to the laundry list of issues with Arms Week, such as "It's not actually being possible to complete Rank 15 without spending Silver/using leftover Reroll Chips from Heavy Metal" (see https://www.bungie.net/en/Forums/Post/264901161 ), the "Volatile Mod, Steady Fight" daily challenge is not progressed by completing matches in Arms Week: Hardware either, meaning you have to use a reroll chip, or simply lose out on the XP for this daily. Attached image shows game history, (match completed >1 min ago) and progress still at 0% for the challenge. Edit: It appears to only count them inconsistently. Not every match appears to actually count, it does or doesn't seemingly at random. I suspected it might have been only wins because it did progress from a win, but then it progressed on a loss, and then didn't progress on another win.