What are Internal Transactions
Internal transactions, despite the name (which isn't part of the yellowpaper; it's a convention people have settled on) are not actual transactions. They are also not included directly in the blockchain; they are value transfers that were initiated by executing a smart contract (smart contract Ether or Token transfer).
Certain Ether and Token transfers require calling a smart contract to perform the transfer. These show up as internal transactions and are not indicated on the main ETH transaction history on etherscan.io. There should be a separate tab for "Internal Transactions" when you look up you wallet address in etherscan.io
When withdrawing, you need to make sure that the receiving address supports smart contracts, like MyCrypto.
If you can't see your transaction, please take a look at our article here
If you see that your transaction was successful but you can't see the tokens in your account, please refer to our article about adding a custom token to your MyCrypto Interface here