So I won, had a 3 streak and grade 5 reaper flag. And no portal showed up. Was stuck and was able to get out of it by doing another HG match...only to get stuck indefinitely under water. Sucks because I didn't get credit for the 3 streak, or turning in the flag. So just a FYI that this does happen and there's absolutely nothing you can do. There was also a random boat way out in the water just sitting there...I sunk it after the battle and it wouldn't open the portal either.