And I believe that Outlook 365, even though it's installed on your machine, it involves using the cloud-based service vs the older Office 2007 being fully installed and operational on your computer. The older versions stored files and data on your computer while the 365 version stores many of those items on OneDrive and other web locations. It's why I'm still using an older version of Office and Outlook. "If it ain't broke, ....."
I am familiar that some have used the link below to get things running again. No guarantees though.
https://diagnostics.outlook.com/#/
Hope this helps.
Grif
Finally made the leap - new Dell Latitude laptop, installed Windows 365, migrated Office 2007 Pro files over. Migration smooth. Then Outlook decided to take a drive on the wild side. The search function worked one month. One day fine. Next day - all search terms end with "No Results". Contact Microsoft support - instructions are: Go to File, Options, Indexing Options, settings, modify, uncheck outlook box, restart outlook. Forgot to mention rebuild. Ok, start again. No success. Any search term hangs suspended or random email(s) displayed with no rhyme or reason.
Call in 2 techies. The rebuild scrambles folders, email and still cannot search. The delete folder has long list of empty folders duplicating folders with email. A search works like this: Enter "Jimmy", select all mailboxes, get no email lists with Jimmy. Instead get random email list from multiple email folders. No email with term "Jimmy" at all. Yet reviewing Inbox email, one can see several emails from "Jimmy". Ya just can't see any email from/to/cc "Jimmy" when a search is done.
Even better, the reading pane email is totally unrelated to search term or any of the emails listed. Search on "Jimmy" and reading pane shows html coding interspersed with email from 2011 but no "Jimmy".
The techies are baffled. One gives up. The other still working on it. "Jimmy" why can't Outlook 365 find you?

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