The Outlook 2016 client has been trusted workhorse for email since the full release. However the latest version 15.17.1 seemed to have a strange flashing and crashed view window. It even lost the header and was unable to show a preview plane. The solution was easy fix without hurting the mail profile.
Run up Terminal window on the MAC:
- Type: defaults delete com.microsoft.Outlook (to delete the old preferences)
- Type: killall cfprefsd (to kill the cached prefs)
- Launch Outlook
That fixed the outlook view and everything restored.