From the Coinbase statement "Initially, customers can send ZEC to Coinbase from both transparent and shielded addresses, but only send off Coinbase to transparent addresses. In the future, we’ll explore support for sending ZEC to shielded addresses in locations where it complies with local laws."
Interestingly, you can't buy ZEC in New York or the UK on Coinbase for some reason
From the Coinbase statement "Initially, customers can send ZEC to Coinbase from both transparent and shielded addresses, but only send off Coinbase to transparent addresses. In the future, we’ll explore support for sending ZEC to shielded addresses in locations where it complies with local laws."
Interestingly, you can't buy ZEC in New York or the UK on Coinbase for some reason
https://www.ccn.com/privacy-friendly-cryptocurrency-zcash-goes-live-on-coinbase-com/
Coinbase official post: https://blog.coinbase.com/buy-and-sell-zec-on-coinbase-ccd0bbb642a9