Drag & Drop in Nano version

Hi-- I’m new to Scrivener and am using the Nano version (Windows, 0.0.48) for the first time. I imported .rtf text into Scrivener, it arrived completely unformatted which was a bit of a pain, and now I find I am unable to drag and drop text. I get the ‘can’t drop’ icon (*though when I open the default Scrivener with the introductory text, I am able to drag and drop there).

I have added many scenes as new text, and cannot drag and drop in those files either. Is there a workaround or … ?