I have a macbook air that uses a thunderbolt ethernet adaptor. Even on a switchport that works fine for a desktop PC, when I plug my macbook into my summit 460 G2 running XOS 16 I see the interface light for about 3 seconds, then the interface goes back down.
I use MacbookPro retina and uses thunderbolt ethernet adaptor too. It's works fine for me with any firmware version. Which port on switch are you connected? Your thunderbolt ethernet adaptor are working with another devices?