To sync successfully, the following conditions must be met: AppleWatch is connected to the current iPhone, the EZsheet application is installed on the AppleWatch and running.
Sometimes the connection between the watch and the phone can freeze, especially on the AppleWatch series 1, 2 and 3. Moreover, this happens at the system level. In this case, you need to restart your iPhone and AppleWatch.
Restart your Apple WatchRestart your iPhoneYou can also try different synchronization methods. To do this, you need to make a long press on the synchronization button and select one of the options.