In windows 10…
So I upgraded Inkscape and suddenly dropping images and svgs into an open Inkscape window didn’t load them into the svg. “Import” worked fine from the menus but the drag-and-drop method failed silently.
I was pretty sure the upgrade had broken itself, but as it turns out it had to do with how I was running Inkscape. After the install, it asked “do you want to run Inkscape now”, and I said yes. Apparently, this causes Inkscape to run with elevated permissions, since the installer was in turn running with elevated permissions.
As it happens, running Inkscape with elevated permissions prevents drag and drop file loads. Who knew?
These guys did:
Restarting Inkscape as a normal user solved the problem.
So, something to remember when this happens to you.