1. The app Disable or stuck, so if you have a chance to reboot the target device, please do it.
Or, maybe you should wait until the device has no battery, and it will automatically reboot when it was plugged into a charger.
Notes: There are some “essential settings” you should check if the app suddenly stops working. Visit our support site, and then you can easily see these links.
In case you still keep in your hand the device, please check with the below link to know all essential settings. You can choose by your target device (brand) and version of Android:
Essential settings while install the app on the target device.
1.1. Go to the support site (this site).
1.2. Search keywords “essential settings” or go to the session “Essential settings” or something like that you will see many articles about how to configure these settings on a specific Android version/brand/device.
Maybe an installation again is required if you did not follow the essential settings as above.
Follow it (the guide above), and 90% will resolve your issue.
2. The target device had no internet connection.
Try to check if it has an internet connection. It is not necessary to have an internet connection always, but it should have some time per day to do synchronization.
3. The app was removed from the device.
Removing, or uninstalling the app by someone else, make the Data synchronization will not occur anymore.
If you have a chance to keep the device in your hand, can you try to show the app to make sure?
How to show/hide the icon: visit our support site and search “How to show”