For some reason, I've never had this problem. Maybe you should just keep challenging till you get someone who plays on. If they time out you still "win," though it is not very satisfying.
Open challenge 1201
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It never fails. More than half of the open challenges I create with 1200 as the minimum rating, someone with a record of 0-0 will start a game and then disappear after a move or two. I'd like the option to create a challenge of 1201-1301, etc. Then at least the player has played a game and come back.