From the researches I have done, this is one of the major attributes of a casino with questionable characters, they would delay your withdrawal at first without any much reply then they would cancel it and tell you their security team are scrutinizing your account so it would delay a bit before you could withdraw all these are just to by time and most of them doing this does not have the financial capacity or they are bankrupt and have no money to pay their players. I will advise you to not play with them again and not bother about the casino as they have no funds to bankroll their services.