I'm having problems with one account using an adroid phone with Exchange ActiveSync.
This was after a migration from Exchange 2010 to 2016.
Tried another account on this phone and it Sync'ed fine. Tried the account on another phone and it did not work on that phone either.
OWA for the account works fine.
The account creates on the phone but nothing Sync's.
This is the largest account on the server almost 4.5GB