I just had a game of stadium where in the second round, the enemy freya decided to leave the game. In the third round, the entire team followed her, ending the game by leaving. I didn’t check if I received ranked progress (I kinda skipped through), but I know for a fact that my weekly loot box progress before that game was at 18 and now, it still is at 18, meaning I didn’t get any progress for winning a stadium game.