Hello @jurvis, unfortunately yes, the simulator UUIDs have changed. We are very sorry for the trouble.
We have updated the docs to not to reference any simulator UUIDs at all—because of how easily the UUIDs can change we now suggest only using simulator names in your circle.yml.
We added an example of how to use simulator names both in the xcodebuild command and when pre-starting the simulator in this post. Could you please check the post out and let us know if using the simulator names works for you?
If there is any use case where you can only use simulator UUIDs and not simulator names please let us know.
Thanks.