tl;dr Setup an office 365 Directory Synchronization before a cutover batch was completed. Incremental syncs stopped working. Deactivated DirSync, but didn’t wait the entire suggested 72 hours for it to take effect, but instead wasted a bunch of time troubleshooting something that didn’t need troubleshooting.
I'm posting some information relating to my experience with migrating clients utilizing an aged SBS 2008 server to 2012 R2 Standard/Essentials and Office 365.
I was given two projects, both pretty much identical. A single server running SBS 2008 utilizing Exchange, File Services, and various other roles, all being migrated to Server 2012 R2 and Exchange to Office 365. Neither client utilized SharePoint, and the only difference between the two was that one was running Essentials on their new server, and the other running Standard.
So,...