Never heard of this game, but this issue is now normal in many new site wallet based games. This is why I prefer blockchain based games where no site wallet is required. Each bet and winning happens directly on the blockchain.
Yes that's actually the safest way of gambling. Now in this case i have also not heard about the site but i looked it up and seems it almost a year old and there doesn't seem any problems in past so this can be a mistake from the site some issue going on with it or they are shutting down.