After the update, our Zoobsters from all around the world are still going from the old version to the newest one. Once you're on the most recent version you only play against players that have updated too!
If you have just downloaded it, maybe you'll see yourself is a smaller poll of players compared to when everyone was on the oldest one! But do not worry, this will solve itself after a few hours when everyone is on the same version again! :)
Hope you keep on having lots of fun and see you at the Zoo!