I am new to Azure AD Connect I used to use DirSync only. We have 1 user who was created on the 11th of this month in AD on prem and it never synced to Office 365. I don't see anything like DirSync had where I can actively watch when a user syncs and when it fails. I have done the following:
1. Checked that Azure AD Connect Service is running and restarted it
2. Checked event viewer. I saw error for not establishing a connection on the 11th but stopped within an hour and no errors since that date. I saw these by filtering Event sources box, select the Directory Synchronization
3. Ran the DirectorySyncClientCmd.exe to force a sync. Cmd prompt pulled up and showed it synced successfully
4. I checked the user in AD and ADSEI Edit and see the attributes are the same for a known good working users
5. I deleted user today and recreated and created a TEST user then ran DirectorySyncClientCmd.exe but after 20 min do not see on 365 console portal.
6. Checked and ran the IDcheck tool and it doesn't show this user at all.