Hi everyone.
I've been battling an issue since Friday evening with regards to an Azure AD Connect no longer synchronizing in a timely fashion.
We have multiple on premise DC's, and 1 hosted in Azure.
This past Friday, I received an automated email from Microsoft stating:
>On **Saturday, 21 July 2018 00:16:55 GMT**, Azure Active Directory did not register a synchronization attempt from the Identity synchronization tool in the last 24 hours for <organization URL here>
>
>You can troubleshoot this issue by running the Directory Synchronization troubleshooter on the server that has Azure Active Directory identity synchronization tools installed.
So in an attempt to fix, I tried to update to the latest AD Sync tool which I believe is currently 1.1.819.0.
After some digging around online and initializing a MS ticket, it turns out that there was a global issue with the latest patch Tuesday (July, 2018) updates that caused massive CPU spikes on the AzureADConnectHealthSyncMonitor service process. A temporary workaround was to disable this service, and sure enough CPU utilization went down and back to normal, however the issue I'm facing seems to be slightly related - but I can't quite put my finger on it. MS has yet to respond to me over the weekend. Must be too busy.
Normally the typical process of syncing after we add our users to AD is to perform a Delta sync (not a full sync) using this command in the PowerShell which takes less than 30 seconds to complete.
`Start-ADSyncSyncCycle -PolicyType delta`
Within the AD Synchronization service manager - items listing in succession from bottom to top, ex:
* [OFFICE365.onmicrosoft.com](https://OFFICE365.onmicrosoft.com) Export
* [OFFICE365.onmicrosoft.com](https://OFFICE365.onmicrosoft.com) Delta Synchronization
* [domain.com](https://domain.com)Delta Synchronization
* [OFFICE365.onmicrosoft.com](https://OFFICE365.onmicrosoft.com) Delta Import
* [domain.com](https://domain.com)Delta Import
The issue is the process is hanging on the second one (from bottom), [OFFICE365.onmicrosoft.com](https://OFFICE365.onmicrosoft.com) Delta Import. It successfully replicates the local AD servers and the one in the cloud, however when it comes to communicating with Office365, it just runs for over 24 hours and does not finish.
Things I've noticed is attempting to stop the AD Sync service though the services.msc seem to hang on "Stopping" and do not stop naturally, I have to kill the miiserver.exe process manually. The service automatically starts again and immediately runs the scheduler task and kicks off the delta sync and continues where it left off, but again, it locks up.
Another issue is the UI for miisclient.exe occasionally locks up where I cannot even stop the connector tasks, they constantly say running, and when I highlight and click stop, nothing happens.
I've gone ahead and removed updates KB4054590 - Server 2016 = 4.7.2 DotNet as well as KB4054566 as per the article I found online to fix the CPU lockup issue related to AD Sync, and still at a standstill with this.
Any assistance would be greatly appreciated.