"At this point the only remaining problem is that Sent items are showing up in the wrong place? " - That is correct. They are showing up under a different data file (and they are apparently the ONLY things in that data file.)

On my version of Outlook (the one that is part of the stand alone, desktop version of Office 2019 in the U.S.), if I follow the directions in the article you cite, I only get options for saving Drafts of messages before they are sent. Mine appear AFTER the message has been sent, under Sent, in a data file that appears to exist only for them to have a place to go. I still haven't be able to figure out how to make them appear in the one and only Data file that I am now using.

The one thing I haven't tried is closing that whole data file and just hoping it will go to the only one left open. But I'd feel more comfortable doing that if someone has already tried this and can confirm that it will work.

Thanks.