I’m confused about the DT Safari extension that I have installed. When I have a PDF open in Safari, I am unable to use the DT extension button to send the PDF to DT. Why?
The PDF options in the DT extension are essentially the same as the Print > PDF action. Printing a PDF to a PDF is not generally not supported in Safari. To get a displayed PDF from Safari to DT, save it. For example, install the Inbox in Finder’s places (see Help > Install Add-ons) and save there.