Very similar scenario - bloody gutted!!
Made the cut for the elimination round of the latest Showdown event. Was playing my 3rd game, when opponents connection failed after 2nd hole. Game screen showed that we were waiting for my opponent's connection for ages - I DID NOT FORFEIT THE GAME AT ANY TIME!!
I was -1 after the 2nd game of the round and was -1 in the game that I was playing, therefore nett -2 with another hole to go and also at least 2no shots ahead of my opponent.
After about 15-20mins waiting, I logged in on another device and was amazed to see the message that I had forfeited the game!!!
I lost the coins, didn't get the win credited to me and was given as finishing the elimination round in -1, therefore missing the cut for the final round.
All in all, a shambles....