Not sure why Microsoft have not supplied answer in this thread, but copied from another is answer. It works.
I used zx3junglist answer in a different way. I found a regedit entry for:
Computer\HKEY_CLASSES_ROOT\AppUserModelId\Microsoft.Office.OUTLOOK.EXE.15
But I am using Outlook 2016 (should be OUTLOOK.EXE.16, not 15)
I renamed Computer\HKEY_CLASSES_ROOT\AppUserModelId\Microsoft.Office.OUTLOOK.EXE.15
to
Computer\HKEY_CLASSES_ROOT\AppUserModelId\Microsoft.Office.OUTLOOK.EXE.16
and popups work. When I click the popup, I get the email!
I hope this helps some!
OMG!!!!! It worked!!!! Thank you Thank you Thank you!!!!! It's been a loooooong 4 months!!! Microsoft support is extremely deficient, just horrible and pointless and that's putting it very very lightly, but these forums are gold!!! Thanks!!!!