Check these things:
1. Verify that the ZMM Enterprise Application is running.
The best way to ensure the ZMM Enterprise Application is running is to go into it. Opening the application ensures that it is running on the device.
Please note that the application may stop running in the following situations:
If the user double taps the home button and closes the running application
If the device is turned off or rebooted
If the OS closes the application to regain the use of memory
Select the device Settings and tap Location Services. Ensure that it is set to "ON" for ZMM.
When the ZMM Enterprise Application is not running.
Please note that when the device does not sync on its regular schedule, it does not affect device security. When using the Apple Push Notification Service Certificate, any changes made for a user sync to the phone regardless of the device App sync. Also, all of the profiles loaded on the device will continue to enforce the required settings.
However, while the device application is not syncing, it will not send the following to the ZMM server (viewable in Smart Devices and Users):
Device Location, if the user's Policy Suite is set to track this
Device statistics, such as battery level and signal strength