You can view most cryptocurrency transactions on the network's respective blockchain, which records and verifies the legitimacy of transactions. However, when transferring from a Coinbase account to another Coinbase account, the transactions occur off the blockchain. This makes confirmation instantaneous, causes transactions to be fee-less, and allows for micro-transactions as small as one satoshi (0.00000001 bitcoin). For these "off-chain" transactions, you won't be able to view the bitcoin transfer in the blockchain, and there won't be an "Advanced Details" link when you click on the transaction.
