Have you contacted their support?
indeed, i have contacted support before posting here. they told me - "During upgrading system, withdrawal to other available address on USD platform will be restricted". but i would like to know maybe where is any tricks or something...
With exchanges you cannot play any tricks to get the withdrawal into the external address. The reason is that based on their processing procedure they will be having rights to stop the transaction or make the transaction not withdrawable for limited time period.