Due to the latest updates from Microsoft, Azure AD Connect Health for Sync, somhow got “broken” giving headaches for the admins with this:
Microsoft.Online.Reporting.MonitoringAgent.Startup high cpu.
Luckily the fix is simple – go install the LATEST AAD Connect tool, and you are good to go
https://www.microsoft.com/en-us/download/details.aspx?id=47594