I have never heard of that exchange before but I think if he is able to withdraw his fund then that is fine. The main aim of trading  is to keep making profits and if op is making a consistent profits on the exchange then that is fine and I think he should keep trading but just like you have written, he should try making some withdrawal to check of the exchange will credit his withdrawal. I know there are so many exchanges that are still growing that are not known to the general market yet. I hope he is going to get paid of his winning trying to make some withdrawal.