Hmm... I'm not sure how that would happen. When you say you won, did you receive a "You Won!" Message or did you see the enemy health bar go to zero? If it was the health bar (red) that doesn't actually end the fight, it only puts the opponent in a "Downed" state where they are at a disadvantage. You only win when your opponent's stamina goes to 0 and they have no Huanjing left.
If you did receive a "You Won!" Message or fully depleted the opponent stamina but the match still isn't ending, can you check Application->BattleGameDB->data->victoryTimer and Application->BattleGameDB->data->combatState->opponentEndurance in the dev console? These variables manage the end of the fight.
Also, did you reload the game while there was a popup open?