Reproduced on Win7 Inkscape 0.91 using an *unsaved* source document.
Workaround: Saving the source document. Works for both putting the svg beside the .png's, and somewhere else.
Reproduced on Win7 Inkscape 0.91 using an *unsaved* source document.
Workaround: Saving the source document. Works for both putting the svg beside the .png's, and somewhere else.