I found this issue occurs in cooperation with Illustrator.app. I use it as due to a bug in inkscape 0.46 lines are not shown as they should be. So I open the file in Illustrator, resize it, save it and then start working in inkscape. Probabely, as the 0.46 bug will be fixed in 0.47, this issue will not occur. Therefore - maybe just wait…
I found this issue occurs in cooperation with Illustrator.app. I use it as due to a bug in inkscape 0.46 lines are not shown as they should be. So I open the file in Illustrator, resize it, save it and then start working in inkscape. Probabely, as the 0.46 bug will be fixed in 0.47, this issue will not occur. Therefore - maybe just wait…