Calendar not syncing correctly from Outlook.

Calendar not syncing correctly from Outlook.

I have my business email setup as an exchange activesync account in Outlook 2016.  Mail and contacts are syncing fine but not all events are syncing on the calendar.  Only some of them show up on the website and then on my phone.
I've tried saving my entire calendar as a .ics file and uploading it to zoho.com and then I get some appts showing at the wrong time and still not all of them show up or sync out to the phone.