On one of my projects, we have migrating over from ESET to Microsoft Defender ATP for Endpoint Azure/Microsoft365 organization which subscribes to an E5 license for each user that is provisioned with a Windows device. We have begun rolling out Microsoft Defender for Endpoints to the devices which are AzureAD Joined and Intune MEM managed.
After the initial device; the remaining devices are put in a Group which has a Windows configuration assigned to it; with Defender settings. The devices have the ESET uninstalled and added to the group. The first few devices were onboarded successfully with no issues. The recent 3 devices status is Onboarded with MEM managed; but the status is "Defender Antivirus not active".