I withdrew a coin to an external wallet, but it hasn’t arrived?

Depending on the blockchain, your withdrawal may just still be pending. Certain coins can be very slow depending on the load on their network. You can see the transaction ID of your withdrawal in your withdrawal history under Accounts.

If your transaction has already been confirmed but you don’t see it in your destination wallet, you will have to contact the receiving wallet provider for support. They will need the transaction ID to locate your coins, you can safely give it to them via their support channels.