Recently I came across a situation where customer was trying to use ConfigMgr and Mobile Device Management (MDM) solutions like Windows Intune to manage Windows 8.1 machines.
When a Windows 8.1 machine is Domain Joined or in work group and Installed with ConfigMgr client for system management, you cannot manage this machine using any other MDM solutions.
When I try to understand how it is restricted, I found that ConfigMgr Client installation sets a Registry value as below.
Name : ExternallyManaged
Type : REG_DWORD
Value : 1
The reason for this is to avoid managing the same device using multiple management solutions. It is not required to manage the same machine using multiple solutions.
This is by design. Hope this helps.
Support Escalation Engineer | Microsoft System Center Configuration Manager
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