Mac Outlook 2016 Search returns "No Results" after migration from 2016 Macbook Pro running High Sierra to new 2019 Macbook Pro running macOS Mojave 10.14.5

Update: While I wasn't able to find a more surgical solution to this problem, Microsoft Outlook Support suggested that I uninstall/reinstall Mac Office 2016.  I was more than a little reluctant to go this route because it involved removing folders from ~/Library which always makes me nervous (if you've done this with another application only to find that your Mac won't boot the next time, you know what I mean).

After reinstalling Outlook (be sure to follow the directions to save folders that contain your mailbox data in case you need it), Search in Outlook started to work!  Since my mailboxes are imap (vs. pop), I just let Outlook rebuild all of the mailboxes on my Mac (which took another 6 hours).

So I'm left thinking that this issue has something to do with how Migration Assistant (in Mojave) handles the transfer of files from a High Sierra computer running Mac Office 2016 to a new one running Mojave.

If you are having trouble with Outlook 2016 for Mac search on Mojave, here's what to do to see if you have this problem and whether uninstalling/reinstalling Office 2016 for Mac might help you:

1. If you click on the magnifying glass icon in the top right (Spotlight), and type some text from an email that you can see in Outlook, does Spotlight find the email message?

• If so, then continue to step 2
• If not, this means that your email messages have not been indexed by Spotlight. There are many articles that detail how to force a re-indexing, here's one: https://www.repairwin.com/fix-outlook-for-mac-search-not-working-no-results/

2. Open the Terminal application and type the following:

mdfind -count "kMDItemKind" == "olk15_message"

You should see "0" returned. The "mdfind" command is searching the Spotlight index for all items that have the type "olk15_message" which is an Outlook email file.

Now type:

mdfind -count "kMDItemKind" == "Document"

After a short wait, you will see the number of items that have the type "Document". Depending on how many files you have, this can be a decently large number.  More than likely, your email messages have the "Document" attribute for kMDItemKind instead of "olk15_message". You can verify this using the steps in an earlier post that use the command "mdls"

3. At this point, I uninstalled and reinstalled Office 2016 for Mac

• Be sure you do a backup of your Mac just in case
• Be sure you copy the mailbox folders to your Desktop as the uninstallation process will remove them (this is in the instructions)
• Here's the uninstall instructions: https://support.office.com/en-us/article/uninstall-office-for-mac-eefa1199-5b58-43af-8a3d-b73dc1a8cae3
• Here's the installation instructions (for Office 2016 for Mac, not Office 365): https://support.office.com/en-us/article/download-and-install-or-reinstall-office-2016-or-office-2013-7c695b06-6d1a-4917-809c-98ce43f86479

4. Open Outlook and recreate your email accounts. If you have imap, Outlook will just rebuild your emails from your email server.  

Hope this helps people who just bought a new Mac (running Mojave) that used Migration Assistant to upgrade from a Mac (running High Sierra) (via Target Disk mode - not sure this matters, but just in case). 

I ended up spending countless hours over what should have been a more pleasant experience.  Hope this saves you some time!

Extra credit:

• Here's some interesting reading for those technically inclined about how Spotlight works (which Mac Outlook 2016 uses for searching) - how meta data importers (mdimporters) work, etc. https://developer.apple.com/library/archive/documentation/Carbon/Conceptual/MetadataIntro/MetadataIntro.html#//apple_ref/doc/uid/TP40001268