When your pet is at one of your designated Places that have Wi-Fi setup, the Whistle 3 will be in power save mode. When the Whistle 3 is in Power Save Mode, the Update Location and Track functions are unavailable.
You can learn more about power save mode here.
If you have setup your Place to be larger than the 35-meter radius minimum, then your pet may be able to spend time within your safe place while away from your Wi-Fi connection. When the Whistle is away from Wi-Fi, the Update Location and Track function's will be available.