If such situation happens to you, how would you react? What a person even can do in this situation? Go away with chips? Give chips to someone else and let him cash out? Contact lawyer?
If there is evidence that you followed the rules and didn’t go against any, then you have every right to cash out your money. However, when the casino tries to make no attempt to do so, then suing them and using the law is the only way you can get whatever you want.
But before you sue the casino, you have to be sure they have truly decided not to cash you out, or if it is just a delay that is common with some casinos, because some casinos are fond of delaying gamblers from cashing out their wins.