To me if you have been using that site to gamble and you also made some withdrawals from the casino there is nothing to worry about, I think you should just have patient while they proceed everything manually and I like know manual withdrawal takes more longer time than automatic withdrawal.
A slight delay for manual approval isn't a problem here. I think OP doesn't mind waiting for a few hours or even a day. But when a withdrawal takes a few days, and suddenly the number of scam accusations increases against a casino, that is where the problem is. I can see at least five scam accusation threads against them on the first page of the scam accusation board.
I didn't check if any of them have been solved lately. If there are scam accusations and the casino solves them, then there are no issues. Let's see if the OP gets a response from the Shuffle team. They are reputed enough and I hope they will settle these cases.