This spring, I updated all of our users to Win10 and Office 2016 (from Win7/Office 2010). These were clean installs, not upgrades. Ever since, a number of users have had frequent occurrences of their .ost files becoming corrupted. (Outlook can't open, saying that it can't open the .ost file.) If I just delete the .ost, Outlook crashes on next start-up. I have to delete it, then completely reboot the machine before it will finally let me re-open Outlook.
I've tried re-creating profiles, looking for add-ons to disable (there aren't any), starting it in safe mode, etc... nothing works except deleting the ost and rebooting. And then the issue often just comes back later (usually the next time they go to restart Outlook). We're running Exchange Online through O365, but everyone uses regular Outlook 2016 desktop client for access, which is where the problem lies. We never had these issues with the same server when people were using Win7/Office 2010, and now I'm getting at least a few a week.
I've seen some other people talking about the same or similar issues, but I haven't seen any real resolutions (just the workaround of deleting the .ost). This isn't a fix - especially for those of us that have limited bandwidth. It's quite detrimental to our operation to have a few gigs of email re-downloading every day. If anyone has any suggestions of where to look to try to track down a real cause/solution for this, I'd be very appreciative.