Enrolled mobile devices might not work as expected, if a user source is deleted and the same user source is re-configured.
Source:
ZENworks Mobile Management
Explanation:
If a configured user source is deleted and the same user source is configured again, then you will be unable to manage mobile devices enrolled using the earlier user source.
Action:
Re-enroll the devices. As a best practice, ensure that you delete the device objects of these devices that are already present in ZCC and then re-enroll these devices.