Comment 3 for bug 1715467

I can confirm that the PDF import dialog is opened in a strange position.

For the main Window I think you're seeing expected behavior (i.e. I can't notice anything strange):
- You probably have checked "Don't save window geometry"
  in Preferences -> Interface -> Window)
- This results in the Inkscape window to be opened in the top left
  of your *primary* display (might be your leftmost monitor)
- If the PDF import opens a new window it opens in the position
  Inkscape would start in when you normally start it
- If you have an empty document and the PDF import re-uses the current
  window and will not change position at all.

If you don't want Inkscape do launch in a default position enable "Remember and use last window's geometry (which works as desired on my machine)