Using older versions of Outlook for Mac in business environments
I had this same problem too. Microsoft Support informed me that the new Outlook version has been released for testing purposes and they have not released all the features - this includes the import and export functions. They did not give an estimated timeframe for when the rest of the features will be available, which doesn't inspire confidence considering it's been over year since the new Outlook was released.
The legacy version of Outlook is the normal version with all the features available so like the others here, I was able to use the export/import features when I reverted back the legacy version. You can switch between the two versions by going Outlook -> New Outlook.