Hey guys, I ran into the same problem as well. Power Saving was already off, auto-sync already enabled, tried variations of pulling data, etc. For those of us syncing with Office365 via a work account, oof the posts here mentioned going into that portal. I visited IT, they knew what page I was referring to, and subsequently they found *two* phones listed. One of them was my old S4 I recently traded in.
To be doubly safe, we deleted both phones from the site, then deleted the account from my phone and reloaded it. Something happened this time that I don't recall seeing previously: after establishing a successful handshake with the email server, a notification occurred on the S7. The IT person clicked it and then affirmed some security question relating the account to the phone. So far so good, and will report back here if it goes south on me again.