There is absolutely no way that any "invenstigation" or security check takes (or should take) 10 business days. Its way more likely that they are stalling for time.
Stalling for what exactly? Imo there is no point to stall unless they are really going to check with their live games provider. This 10 business days could mean that they are preparing for the withdrawal since they could be having their cold wallet in form of fiat so they need to buy btc for now