Why 'tracking code' in 'Natural Search' ?

If I'm reading your table correctly, under "2020HQSEM_..." Campaign (which is classified from your Tracking Code), under the "Search Engines" Referrer Type, you have "Paid Search" Search Engine, and under that, you have "Natural" and "Paid" Marketing Channels.

Is that correct?

If so, then the most likely reason is that of expiries, or scope.

• Tracking Codes normally have expire at "Week".
• Referrer Type and Search Engine have expire at "Visit" usually, though strictly speaking, they are set every time the user enters your site from somewhere else.
• Marketing Channels don't normally have an expiry, but are set per hit based on your Marketing Channel Processing Rules.

As you can see, given the different expiries for each dimension, you then end up with results like in your table. But your table's results still make sense. You just have to think a bit more about how the various expiries come into play.