Same thing happened to me. We tied in banners, but opponent got the win even though I have the higher GP (see screenshots). Even though GP changes after lock-in period, I don't see how the opponent could reduce their GP by 500-600k (our GP difference) since I don't increase my GP much since then.
Also @sedeller : customer service is wrong. You can't have both lose, we're supposed to win according to the old Grand Arena Rules. How are they going to do the matchmaking for Round 2 if they have 3 winners and 5 losers?
Tiebreakers: In the rare occasion of the event ending with tied banners, the player with the higher GP will win. In the extremely rare chance of equal Banners and equal GP, a random player wins.
From: https://forums.galaxy-of-heroes.starwars.ea.com/discussion/189068/title-update-14-12-4-2018
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