Shot below shows classes associated with "PDF-Xchange Preview Handler".

Shot below shows the classes associated with "PDF-XChange PDF Preview Provider". This is the handler that came with the PDF-Xchange Viewer program.

I unchecked the classes under the "PDF-Xchange Preview Handler" and then associated them with the "PDF-Xchange PDF Preview Provider."
Shot below shows the three classes associated with "PDF-XChange PDF Preview Provider".

Now the PDFs are displaying properly in the Native preview pane.
I'm not sure that I did the best possible fix here - I could have just tried associating the PDF extension with the desired handler.
More info on the association editor here - https://www.thewindowsclub.com/preview- ... e-explorer
The utility is old and a bit hard to find, I've uploaded it here - https://1drv.ms/u/s!ApvlyzaJFXSxy90nEPJ ... w?e=iHwOdm . I had no problems with it, but do your usual due diligence.