Drag from Scrivener converting PDF to TIFF

MacbookPro: Mojave…

I like to use Scrivener for compiling information on a variety of current projects I am working on.
During that process I need to email some of the pdfs that I have put in Research.
When I try to drag them from the binder and drop them they are converted to TIFFS.
Please advise.

The File -> Export command will export research files in their original format.

Alternatively, you can Import -> Research Files as Aliases to leave them outside the project, and therefore accessible via Finder.