That also happens with the Xbox One version. If there's a group/pod of dolphins in one area, they will freeze up and stay like that until you reload the world.
It was my Xbox live connection. It went down for a few minutes.
Forgot to mention, when i exited the game and got back on, the Acheivements tab was blank. And now none of my Acheivements show up.
This is also happening on the Xbox One console aswell! Its so annoying when building.