I've launched QubitDice
http://dice.qbit-chain.com/ a blockchain gambling service like SatoshiDice. It's in a beta now so maximum bets have low values.
Same prob. Sent 3 x 50 bets only 2 showing in history.
GUmQJHSw9A5av7AE.....
It looks like my first bet payout went to the wrong address GLZsrfbHEJggbX2N instead of GUmQJHSw9A5av7AE.
Time and odds tie up with what I sent.
Payout goes to the address specified in the first transaction output. Your wallet has a lot of addresses not only that shown in GUI. You can list all your addresses with coins using listaddressgroupings command in console.