My Cryptocurrency withdrawal says it has been withdrawn from my NDAX wallet but has not yet landed on the other exchange/external wallet.
Once the cryptocurrency has left your NDAX wallet it has been submitted on the blockchain. Each external exchange/wallet have their own protocols before they release the funds into your account. Please contact your external wallet/exchange support for details.
When sending coins to NDAX we require a certain set of confirmations on the blockchain before they show. Bitcoin requires 3 confirmations before it will show in your NDAX account.