After enabling Lockdown on a domain controller running Server 2012R2, Microsoft's Synchronization Service Manager application included with Azure AD Connect would not function correctly. I was also experiencing the Microsoft Azure AD Sync service failing and restarting when opening the Azure AD Connect application. Within the Synchronization Service Manager application, the ADDS Delta import would show with status of success when trying to sync, but the Azure AD connector's delta import would show a status of stopped-server.
I unlocked the server within Central Admin and was able to resume syncing correctly. After locking down again, it stopped. I had to add Lockdown policy folder exceptions in order for it to work properly when locked down:
- C:\Program Files\Microsoft Azure Active Directory Connect
- C:\Program Files\Microsoft Azure AD Connect Health Sync Agent
- C:\Program Files\Microsoft Azure AD Sync
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